Phosphorous-linked oligomeric compounds and their use in gene modulation

ABSTRACT

Oligonucleotide compositions comprising first and second oligonucleotides are provided wherein at least a portion of the first oligonucleotide is capable of hybridizing with at least a portion of the second oligonucleotide, at least a portion of the first oligonucleotide is complementary to and capable of hybridizing to a selected target nucleic acid, and at least one of the first or second oligonucleotides includes at least one nucleotide having a modified phosphorous-containing internucleoside linkage. Oligonucleotide/protein compositions are also provided comprising an oligonucleotide complementary to and capable of hybridizing to a selected target nucleic acid and at least one protein comprising at least a portion of an RNA-induced silencing complex (RISC), wherein at least one nucleotide of the oligonucleotide has a modified phosphorous-containing internucleoside linkage.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 10/860,455 filed Jun. 3, 2004, which is a continuation in part of U.S. patent application Ser. No. 10/700,688, filed Nov. 4, 2003, which is a continuation in part of U.S. patent application Ser. No. 10/460,433, filed Jun. 12, 2003 each of which is incorporated herein by reference in its entirety. U.S. patent application Ser. No. 10/860,455 also claims the benefit of U.S. Provisional Patent Application Ser. No. 60/423,760, filed Nov. 5, 2002, which is incorporated herein by reference in its entirety.

SEQUENCE LISTING

The present application is being filed along with a Sequence Listing in electronic format. The Sequence Listing is provided as a file entitled CHEM0003USC1SEQ_ST25.txt, created on Aug. 24, 2015 which is 44 Kb in size. The information in the electronic format of the sequence listing is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention provides modified oligonucleotides that modulate gene expression via a RNA interference pathway. The oligonucleotides of the invention include one or more modifications thereon resulting in differences in various physical properties and attributes compared to wild type nucleic acids. The modified oligonucleotides are used alone or in compositions to modulate the targeted nucleic acids. In preferred embodiments of the invention, the modified oligonucleotides contain at least one modified phosphorous-containing internucleoside linkage.

BACKGROUND OF THE INVENTION

In many species, introduction of double-stranded RNA (dsRNA) induces potent and specific gene silencing. This phenomenon occurs in both plants and animals and has roles in viral defense and transposon silencing mechanisms. This phenomenon was originally described more than a decade ago by researchers working with the petunia flower. While trying to deepen the purple color of these flowers, Jorgensen et al. introduced a pigment-producing gene under the control of a powerful promoter. Instead of the expected deep purple color, many of the flowers appeared variegated or even white. Jorgensen named the observed phenomenon “cosuppression”, since the expression of both the introduced gene and the homologous endogenous gene was suppressed (Napoli et al., Plant Cell, 1990, 2, 279-289; Jorgensen et al., Plant Mol. Biol., 1996, 31, 957-973).

Cosuppression has since been found to occur in many species of plants, fungi, and has been particularly well characterized in Neurospora crassa, where it is known as “quelling” (Cogoni and Macino, Genes Dev. 2000, 10, 638-643; Guru, Nature, 2000, 404, 804-808).

The first evidence that dsRNA could lead to gene silencing in animals came from work in the nematode, Caenorhabditis elegans. In 1995, researchers Guo and Kemphues were attempting to use antisense RNA to shut down expression of the par-1 gene in order to assess its function. As expected, injection of the antisense RNA disrupted expression of par-1, but quizzically, injection of the sense-strand control also disrupted expression (Guo and Kempheus, Cell, 1995, 81, 611-620). This result was a puzzle until Fire et al. injected dsRNA (a mixture of both sense and antisense strands) into C. elegans. This injection resulted in much more efficient silencing than injection of either the sense or the antisense strands alone. Injection of just a few molecules of dsRNA per cell was sufficient to completely silence the homologous gene's expression. Furthermore, injection of dsRNA into the gut of the worm caused gene silencing not only throughout the worm, but also in first generation offspring (Fire et al., Nature, 1998, 391, 806-811).

The potency of this phenomenon led Timmons and Fire to explore the limits of the dsRNA effects by feeding nematodes bacteria that had been engineered to express dsRNA homologous to the C. elegans unc-22 gene. Surprisingly, these worms developed an unc-22 null-like phenotype (Timmons and Fire, Nature 1998, 395, 854; Timmons et al., Gene, 2001, 263, 103-112). Further work showed that soaking worms in dsRNA was also able to induce silencing (Tabara et al., Science, 1998, 282, 430-431). PCT publication WO 01/48183 discloses methods of inhibiting expression of a target gene in a nematode worm involving feeding to the worm a food organism which is capable of producing a double-stranded RNA structure having a nucleotide sequence substantially identical to a portion of the target gene following ingestion of the food organism by the nematode, or by introducing a DNA capable of producing the double-stranded RNA structure (Bogaert et al., 2001).

The posttranscriptional gene silencing defined in Caenorhabditis elegans resulting from exposure to double-stranded RNA (dsRNA) has since been designated as RNA interference (RNAi). This term has come to generalize all forms of gene silencing involving dsRNA leading to the sequence-specific reduction of endogenous targeted mRNA levels; unlike co-suppression, in which transgenic DNA leads to silencing of both the transgene and the endogenous gene.

Introduction of exogenous double-stranded RNA (dsRNA) into Caenorhabditis elegans has been shown to specifically and potently disrupt the activity of genes containing homologous sequences. Montgomery et al. suggests that the primary interference affects of dsRNA are post-transcriptional. This conclusion being derived from examination of the primary DNA sequence after dsRNA-mediated interference and a finding of no evidence of alterations, followed by studies involving alteration of an upstream operon having no effect on the activity of its downstream gene. These results argue against an effect on initiation or elongation of transcription. Finally using in situ hybridization they observed that dsRNA-mediated interference produced a substantial, although not complete, reduction in accumulation of nascent transcripts in the nucleus, while cytoplasmic accumulation of transcripts was virtually eliminated. These results indicate that the endogenous mRNA is the primary target for interference and suggest a mechanism that degrades the targeted mRNA before translation can occur. It was also found that this mechanism is not dependent on the SMG system, an mRNA surveillance system in C. elegans responsible for targeting and destroying aberrant messages. The authors further suggest a model of how dsRNA might function as a catalytic mechanism to target homologous mRNAs for degradation. (Montgomery et al., Proc. Natl. Acad. Sci. USA, 1998, 95, 15502-15507).

Recently, the development of a cell-free system from syncytial blastoderm Drosophila embryos, which recapitulates many of the features of RNAi, has been reported. The interference observed in this reaction is sequence specific, is promoted by dsRNA but not single-stranded RNA, functions by specific mRNA degradation, and requires a minimum length of dsRNA. Furthermore, preincubation of dsRNA potentiates its activity demonstrating that RNAi can be mediated by sequence-specific processes in soluble reactions (Tuschl et al., Genes Dev., 1999, 13, 3191-3197).

In subsequent experiments, Tuschl et al, using the Drosophila in vitro system, demonstrated that 21- and 22-nt RNA fragments are the sequence-specific mediators of RNAi. These fragments, which they termed short interfering RNAs (siRNAs), were shown to be generated by an RNase III-like processing reaction from long dsRNA. They also showed that chemically synthesized siRNA duplexes with overhanging 3′ ends mediate efficient target RNA cleavage in the Drosophila lysate, and that the cleavage site is located near the center of the region spanned by the guiding siRNA. In addition, they suggest that the direction of dsRNA processing determines whether sense or antisense target RNA can be cleaved by the siRNA-protein complex (Elbashir et al., Genes Dev., 2001, 15, 188-200). Further characterization of the suppression of expression of endogenous and heterologous genes caused by the 21-23 nucleotide siRNAs have been investigated in several mammalian cell lines, including human embryonic kidney (293) and HeLa cells (Elbashir et al., Nature, 2001, 411, 494-498).

The Drosophila embryo extract system has been exploited, using green fluorescent protein and luciferase tagged siRNAs, to demonstrate that siRNAs can serve as primers to transform the target mRNA into dsRNA. The nascent dsRNA is degraded to eliminate the incorporated target mRNA while generating new siRNAs in a cycle of dsRNA synthesis and degradation. Evidence is also presented that mRNA-dependent siRNA incorporation to form dsRNA is carried out by an RNA-dependent RNA polymerase activity (RdRP) (Lipardi et al., Cell, 2001, 107, 297-307).

The involvement of an RNA-directed RNA polymerase and siRNA primers as reported by Lipardi et al. (Lipardi et al., Cell, 2001, 107, 297-307) is one of the many intriguing features of gene silencing by RNA interference. This suggests an apparent catalytic nature to the phenomenon. New biochemical and genetic evidence reported by Nishikura et al. also shows that an RNA-directed RNA polymerase chain reaction, primed by siRNA, amplifies the interference caused by a small amount of “trigger” dsRNA (Nishikura, Cell, 2001, 107, 415-418).

Investigating the role of “trigger” RNA amplification during RNA interference (RNAi) in Caenorhabditis elegans, Sijen et al revealed a substantial fraction of siRNAs that cannot derive directly from input dsRNA. Instead, a population of siRNAs (termed secondary siRNAs) appeared to derive from the action of the previously reported cellular RNA-directed RNA polymerase (RdRP) on mRNAs that are being targeted by the RNAi mechanism. The distribution of secondary siRNAs exhibited a distinct polarity (5′-3′; on the antisense strand), suggesting a cyclic amplification process in which RdRP is primed by existing siRNAs. This amplification mechanism substantially augmented the potency of RNAi-based surveillance, while ensuring that the RNAi machinery will focus on expressed mRNAs (Sijen et al., Cell, 2001, 107, 465-476).

Most recently, Tijsterman et al. have shown that, in fact, single-stranded RNA oligomers of antisense polarity can be potent inducers of gene silencing. As is the case for cosuppression, they showed that antisense RNAs act independently of the RNAi genes rde-1 and rde-4 but require the mutator/RNAi gene mut-7 and a putative DEAD box RNA helicase, mut-14. According to the authors, their data favor the hypothesis that gene silencing is accomplished by RNA primer extension using the mRNA as template, leading to dsRNA that is subsequently degraded suggesting that single-stranded RNA oligomers are ultimately responsible for the RNAi phenomenon (Tijsterman et al., Science, 2002, 295, 694-697).

Several recent publications have described the structural requirements for the dsRNA trigger required for RNAi activity. Recent reports have indicated that ideal dsRNA sequences are 21 nt in length containing 2 nt 3′-end overhangs (Elbashir et al, EMBO (2001), 20, 6877-6887, Sabine Brantl, Biochimica et Biophysica Acta, 2002, 1575, 15-25.) In this system, substitution of the 4 nucleosides from the 3′-end with 2′-deoxynucleosides has been demonstrated to not affect activity. On the other hand, substitution with 2′-deoxynucleosides or 2′-OMe-nucleosides throughout the sequence (sense or antisense) was shown to be deleterious to RNAi activity.

Investigation of the structural requirements for RNA silencing in C. elegans has demonstrated modification of the internucleotide linkage (phosphorothioate) to not interfere with activity (Parrish et al., Molecular Cell, 2000, 6, 1077-1087.) It was also shown by Parrish et al., that chemical modification like 2′-amino or 5-iodouridine are well tolerated in the sense strand but not the antisense strand of the dsRNA suggesting differing roles for the 2 strands in RNAi. Base modification such as guanine to inosine (where one hydrogen bond is lost) has been demonstrated to decrease RNAi activity independently of the position of the modification (sense or antisense). Some “position independent” loss of activity has been observed following the introduction of mismatches in the dsRNA trigger. Some types of modifications, for example introduction of sterically demanding bases such as 5-iodoU, have been shown to be deleterious to RNAi activity when positioned in the antisense strand, whereas modifications positioned in the sense strand were shown to be less detrimental to RNAi activity. As was the case for the 21 nt dsRNA sequences, RNA-DNA heteroduplexes did not serve as triggers for RNAi. However, dsRNA containing 2′-F-2′-deoxynucleosides appeared to be efficient in triggering RNAi response independent of the position (sense or antisense) of the 2′-F-2′-deoxynucleosides.

In one study the reduction of gene expression was studied using electroporated dsRNA and a 25mer morpholino oligomer in post implantation mouse embryos (Mellitzer et al., Mehanisms of Development, 2002, 118, 57-63). The morpholino oligomer did show activity but was not as effective as the dsRNA.

A number of PCT applications have recently been published that relate to the RNAi phenomenon. These include: PCT publication WO 00/44895; PCT publication WO 00/49035; PCT publication WO 00/63364; PCT publication WO 01/36641; PCT publication WO 01/36646; PCT publication WO 99/32619; PCT publication WO 00/44914; PCT publication WO 01/29058; and PCT publication WO 01/75164.

U.S. Pat. Nos. 5,898,031 and 6,107,094, each of which is commonly owned with this application and each of which is herein incorporated by reference, describe certain oligonucleotide having RNA like properties. When hybridized with RNA, these oligonucleotides serve as substrates for a dsRNase enzyme with resultant cleavage of the RNA by the enzyme.

In another recently published paper (Martinez et al., Cell, 2002, 110, 563-574) it was shown that single stranded as well as double stranded siRNA resides in the RNA-induced silencing complex (RISC) together with elF2C1 and elf2C2 (human GERp950) Argonaute proteins. The activity of 5′-phosphorylated single stranded siRNA was comparable to the double stranded siRNA in the system studied. In a related study, the inclusion of a 5′-phosphate moiety was shown to enhance activity of siRNA's in vivo in Drosophilia embryos (Boutla, et al., Curr. Biol., 2001, 11, 1776-1780). In another study, it was reported that the 5′-phosphate was required for siRNA function in human HeLa cells (Schwarz et al., Molecular Cell, 2002, 10, 537-548).

In yet another recently published paper (Chiu et al., Molecular Cell, 2002, 10, 549-561) it was shown that the 5′-hydroxyl group of the siRNA is essential as it is phosphorylated for activity while the 3′-hydroxyl group is not essential and tolerates substitute groups such as biotin. It was further shown that bulge structures in one or both of the sense or antisense strands either abolished or severely lowered the activity relative to the unmodified siRNA duplex. Also shown was severe lowering of activity when psoralen was used to cross link an siRNA duplex.

Like the RNAse H pathway, the RNA interference pathway for modulation of gene expression is an effective means for modulating the levels of specific gene products and, thus, would be useful in a number of therapeutic, diagnostic, and research applications involving gene silencing. The present invention therefore provides oligomeric compounds useful for modulating gene expression pathways, including those relying on mechanisms of action such as RNA interference and dsRNA enzymes, as well as antisense and non-antisense mechanisms. One having skill in the art, once armed with this disclosure will be able, without undue experimentation, to identify preferred oligonucleotide compounds for these uses.

SUMMARY OF THE INVENTION

In certain aspects, the invention relates to oligonucleotide compositions comprising a first oligonucleotide and a second oligonucleotide in which at least a portion of the first oligonucleotide is capable of hybridizing with at least a portion of the second oligonucleotide, and at least a portion of the first oligonucleotide is complementary to and capable of hybridizing to a selected target nucleic acid. At least one of the first or second oligonucleotides includes one or more nucleotides having a modification comprising a phosphorothioate; phosphorodithioate; phosphonate; phosphonothioate; phosphotriester; phosphorothiotriester; phosphoramidate; phosphorothioamidate; phosphinate; boronate; α-D-arabinofuranosyl; or 2′-5′ internucleoside linkage, or at least one of the first or second oligonucleotides includes at least one region of chirally pure internucleoside linkages or at least one region of inverted polarity.

In certain other embodiments, the invention is directed to oligonucleotide/protein compositions comprising an oligonucleotide complementary to and capable of hybridizing to a selected target nucleic acid, and at least one protein comprising at least a portion of a RNA-induced silencing complex (RISC). The oligonucleotide includes at least one nucleotide having a modification comprising a phosphorothioate; phosphorodithioate; phosphonate; phosphonothioate; phosphotriester; phosphorothiotriester; phosphoramidate; phosphorothioamidate; phosphinate; boronate; α-D-arabinofuranosyl; or 2′-5′ internucleoside linkage, or the oligonucleotide includes at least one region of chirally pure internucleoside linkages or at least one region of inverted polarity.

In other aspects, the invention relates to oligonucleotides having at least a first region and a second region where the first region of the oligonucleotide is complementary to and is capable of hybridizing with the second region of the oligonucleotide, and at least a portion of the oligonucleotide is complementary to and is capable of hybridizing to a selected target nucleic acid. The oligonucleotide further includes at least one nucleotide having a modification comprising a phosphorothioate; phosphorodithioate; phosphonate; phosphonothioate; phosphotriester; phosphorothiotriester; phosphoramidate; phosphorothioamidate; phosphinate; boronate; α-D-arabinofuranosyl; 2′-5′ internucleoside linkage, or the oligonucleotide includes at least one region of chirally pure internucleoside linkages or at least one region of inverted polarity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the activity of siRNA and antisense RNA with 2′-5′-linked 3-deoxyoligonucleotides. siPTEN denotes duplex siRNA specific for PTEN mRNA. Inhibition of PTEN mRNA expression in HeLa cells transfected with 150 mM of each construct was measured. Total RNA was harvested and PTEN mRNA reduction was assessed by quantitative RT-PCT and normalized to Ribogreen.

FIG. 2 depicts the activity of siRNA and antisense RNA constructs with 2′,5′-linked oligoribonucleotides. Inhibition of PTEN mRNA expression in HeLa cells transfected with duplex siRNA constructs was measured. Total RNA was harvested and PTEN mRNA reduction was assessed by quantitative RT-PCR and normalized to Ribogreen

FIG. 3 depicts the activity of siRNA and antisense RNA with 2′,5′-linked oligoribonucleotides. Inhibition of PTEN mRNA expression in HeLa cells transfected with duplex siRNA constructs was measured. Total RNA was harvested and PTEN mRNA reduction was assessed by quantitative RT-PCR and normalized to Ribogreen

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides oligomeric compounds useful in the modulation of gene expression. Although not intending to be bound by theory, oligomeric compounds of the invention are believed to modulate gene expression by hybridizing to a nucleic acid target resulting in loss of normal function of the target nucleic acid. As used herein, the term “target nucleic acid” or “nucleic acid target” is used for convenience to encompass any nucleic acid capable of being targeted including without limitation DNA, RNA (including pre-mRNA and mRNA or portions thereof) transcribed from such DNA, and also cDNA derived from such RNA. In a preferred embodiment of this invention modulation of gene expression is effected via modulation of a RNA associated with the particular gene RNA.

The invention provides for modulation of a target nucleic acid that is a messenger RNA. The messenger RNA is degraded by the RNA interference mechanism as well as other mechanisms in which double stranded RNA/RNA structures are recognized and degraded, cleaved or otherwise rendered inoperable.

The functions of RNA to be interfered with can include replication and transcription. Replication and transcription, for example, can be from an endogenous cellular template, a vector, a plasmid construct or otherwise. The functions of RNA to be interfered with can include functions such as translocation of the RNA to a site of protein translation, translocation of the RNA to sites within the cell which are distant from the site of RNA synthesis, translation of protein from the RNA, splicing of the RNA to yield one or more RNA species, and catalytic activity or complex formation involving the RNA which may be engaged in or facilitated by the RNA. In the context of the present invention, “modulation” and “modulation of expression” mean either an increase (stimulation) or a decrease (inhibition) in the amount or levels of a nucleic acid molecule encoding the gene, e.g., DNA or RNA. Inhibition is often the preferred form of modulation of expression and mRNA is often a preferred target nucleic acid.

Compounds of the Invention

In certain aspects, the invention relates to oligomeric compounds that comprise at least one modified phosphorous-containing internucleoside linkage. Such modified internucleoside linkages include, but are not limited to, phosphorothioate; phosphorodithioate; phosphonate; phosphonothioate; phosphotriester; phosphorothiotriester; phosphoramidate; phosphorothioamidate; phosphinate; boronate; α-D-arabinofuranosyl; 2′-5′; and chirally pure internucleoside linkages. In addition, in certain embodiments, the oligomeric compounds of the invention can include at least one backbone region of inverted polarity.

Hybridization

In the context of this invention, “hybridization” means the pairing of complementary strands of oligomeric compounds. In the present invention, the preferred mechanism of pairing involves hydrogen bonding, which may be Watson-Crick, Hoogsteen or reversed Hoogsteen hydrogen bonding, between complementary nucleoside or nucleotide bases (nucleobases) of the strands of oligomeric compounds. For example, adenine and thymine are complementary nucleobases that pair through the formation of hydrogen bonds. Hybridization can occur under varying circumstances.

An oligomeric compound of the invention is believed to specifically hybridize to the target nucleic acid and interfere with its normal function to cause a loss of activity. There is preferably a sufficient degree of complementarity to avoid non-specific binding of the oligomeric compound to non-target nucleic acid sequences under conditions in which specific binding is desired, i.e., under physiological conditions in the case of in vivo assays or therapeutic treatment, and under conditions in which assays are performed in the case of in vitro assays.

In the context of the present invention the phrase “stringent hybridization conditions” or “stringent conditions” refers to conditions under which an oligomeric compound of the invention will hybridize to its target sequence, but to a minimal number of other sequences. Stringent conditions are sequence-dependent and will vary with different circumstances and in the context of this invention; “stringent conditions” under which oligomeric compounds hybridize to a target sequence are determined by the nature and composition of the oligomeric compounds and the assays in which they are being investigated.

“Complementary,” as used herein, refers to the capacity for precise pairing of two nucleobases regardless of where the two are located. For example, if a nucleobase at a certain position of an oligomeric compound is capable of hydrogen bonding with a nucleobase at a certain position of a target nucleic acid, then the position of hydrogen bonding between the oligonucleotide and the target nucleic acid is considered to be a complementary position. The oligomeric compound and the target nucleic acid are complementary to each other when a sufficient number of complementary positions in each molecule are occupied by nucleobases that can hydrogen bond with each other. Thus, “specifically hybridizable” and “complementary” are terms which are used to indicate a sufficient degree of precise pairing or complementarity over a sufficient number of nucleobases such that stable and specific binding occurs between the oligonucleotide and a target nucleic acid.

It is understood in the art that the sequence of the oligomeric compound need not be 100% complementary to that of its target nucleic acid to be specifically hybridizable. Moreover, an oligomeric compound may hybridize over one or more segments such that intervening or adjacent segments are not involved in the hybridization event (e.g., a loop structure or hairpin structure). It is preferred that the oligomeric compounds of the present invention comprise at least 70% sequence complementarity to a target region within the target nucleic acid, more preferably that they comprise 90% sequence complementarity and even more preferably comprise 95% sequence complementarity to the target region within the target nucleic acid sequence to which they are targeted. For example, an oligomeric compound in which 18 of 20 nucleobases of the oligomeric compound are complementary to a target region, and would therefore specifically hybridize, would represent 90 percent complementarity. In this example, the remaining noncomplementary nucleobases may be clustered or interspersed with complementary nucleobases and need not be contiguous to each other or to complementary nucleobases. As such, an oligomeric compound which is 18 nucleobases in length having 4 (four) noncomplementary nucleobases which are flanked by two regions of complete complementarity with the target nucleic acid would have 77.8% overall complementarity with the target nucleic acid and would thus fall within the scope of the present invention. Percent complementarity of an oligomeric compound with a region of a target nucleic acid can be determined routinely using BLAST programs (basic local alignment search tools) and PowerBLAST programs known in the art (Altschul et al., J. Mol. Biol., 1990, 215, 403-410; Zhang and Madden, Genome Res., 1997, 7, 649-656).

Targets of the Invention

“Targeting” an oligomeric compound to a particular nucleic acid molecule, in the context of this invention, can be a multistep process. The process usually begins with the identification of a target nucleic acid whose function is to be modulated. This target nucleic acid may be, for example, a mRNA transcribed from a cellular gene whose expression is associated with a particular disorder or disease state, or a nucleic acid molecule from an infectious agent.

The targeting process usually also includes determination of at least one target region, segment, or site within the target nucleic acid for the interaction to occur such that the desired effect, e.g., modulation of expression, will result. Within the context of the present invention, the term “region” is defined as a portion of the target nucleic acid having at least one identifiable structure, function, or characteristic. Within regions of target nucleic acids are segments. “Segments” are defined as smaller or sub-portions of regions within a target nucleic acid. “Sites,” as used in the present invention, are defined as positions within a target nucleic acid. The terms region, segment, and site can also be used to describe an oligomeric compound of the invention such as for example a gapped oligomeric compound having 3 separate segments.

Since, as is known in the art, the translation initiation codon is typically 5′-AUG (in transcribed mRNA molecules; 5′-ATG in the corresponding DNA molecule), the translation initiation codon is also referred to as the “AUG codon,” the “start codon” or the “AUG start codon”. A minority of genes have a translation initiation codon having the RNA sequence 5′-GUG, 5′-UUG or 5′-CUG, and 5′-AUA, 5′-ACG and 5′-CUG have been shown to function in vivo. Thus, the terms “translation initiation codon” and “start codon” can encompass many codon sequences, even though the initiator amino acid in each instance is typically methionine (in eukaryotes) or formylmethionine (in prokaryotes). It is also known in the art that eukaryotic and prokaryotic genes may have two or more alternative start codons, any one of which may be preferentially utilized for translation initiation in a particular cell type or tissue, or under a particular set of conditions. In the context of the invention, “start codon” and “translation initiation codon” refer to the codon or codons that are used in vivo to initiate translation of an mRNA transcribed from a gene encoding a nucleic acid target, regardless of the sequence(s) of such codons. It is also known in the art that a translation termination codon (or “stop codon”) of a gene may have one of three sequences, i.e., 5′-UAA, 5′-UAG and 5′-UGA (the corresponding DNA sequences are 5′-TAA, 5′-TAG and 5′-TGA, respectively).

The terms “start codon region” and “translation initiation codon region” refer to a portion of such an mRNA or gene that encompasses from about 25 to about 50 contiguous nucleotides in either direction (i.e., 5′ or 3′) from a translation initiation codon. Similarly, the terms “stop codon region” and “translation termination codon region” refer to a portion of such an mRNA or gene that encompasses from about 25 to about 50 contiguous nucleotides in either direction (i.e., 5′ or 3′) from a translation termination codon. Consequently, the “start codon region” (or “translation initiation codon region”) and the “stop codon region” (or “translation termination codon region”) are all regions which may be targeted effectively with the antisense oligomeric compounds of the present invention.

The open reading frame (ORF) or “coding region,” which is known in the art to refer to the region between the translation initiation codon and the translation termination codon, is also a region which may be targeted effectively. Within the context of the present invention, a preferred region is the intragenic region encompassing the translation initiation or termination codon of the open reading frame (ORF) of a gene.

Other target regions include the 5′ untranslated region (5′UTR), known in the art to refer to the portion of an mRNA in the 5′ direction from the translation initiation codon, and thus including nucleotides between the 5′ cap site and the translation initiation codon of an mRNA (or corresponding nucleotides on the gene), and the 3′ untranslated region (3′UTR), known in the art to refer to the portion of an mRNA in the 3′ direction from the translation termination codon, and thus including nucleotides between the translation termination codon and 3′ end of an mRNA (or corresponding nucleotides on the gene). The 5′ cap site of an mRNA comprises an N7-methylated guanosine residue joined to the 5′-most residue of the mRNA via a 5′-5′ triphosphate linkage. The 5′ cap region of an mRNA is considered to include the 5′ cap structure itself as well as the first 50 nucleotides adjacent to the cap site. It is also preferred to target the 5′ cap region.

Although some eukaryotic mRNA transcripts are directly translated, many contain one or more regions, known as “introns,” which are excised from a transcript before it is translated. The remaining (and therefore translated) regions are known as “exons” and are spliced together to form a continuous mRNA sequence. Targeting splice sites, i.e., intron-exon junctions or exon-intron junctions, may also be particularly useful in situations where aberrant splicing is implicated in disease, or where an overproduction of a particular splice product is implicated in disease. Aberrant fusion junctions due to rearrangements or deletions are also preferred target sites. mRNA transcripts produced via the process of splicing of two (or more) mRNAs from different gene sources are known as “fusion transcripts”. It is also known that introns can be effectively targeted using oligomeric compounds targeted to, for example, pre-mRNA.

It is also known in the art that alternative RNA transcripts can be produced from the same genomic region of DNA. These alternative transcripts are generally known as “variants”. More specifically, “pre-mRNA variants” are transcripts produced from the same genomic DNA that differ from other transcripts produced from the same genomic DNA in either their start or stop position and contain both intronic and exonic sequences.

Upon excision of one or more exon or intron regions, or portions thereof during splicing, pre-mRNA variants produce smaller “mRNA variants”. Consequently, mRNA variants are processed pre-mRNA variants and each unique pre-mRNA variant must always produce a unique mRNA variant as a result of splicing. These mRNA variants are also known as “alternative splice variants”. If no splicing of the pre-mRNA variant occurs then the pre-mRNA variant is identical to the mRNA variant.

It is also known in the art that variants can be produced through the use of alternative signals to start or stop transcription and that pre-mRNAs and mRNAs can possess more that one start codon or stop codon. Variants that originate from a pre-mRNA or mRNA that use alternative start codons are known as “alternative start variants” of that pre-mRNA or mRNA. Those transcripts that use an alternative stop codon are known as “alternative stop variants” of that pre-mRNA or mRNA. One specific type of alternative stop variant is the “polyA variant” in which the multiple transcripts produced result from the alternative selection of one of the “polyA stop signals” by the transcription machinery, thereby producing transcripts that terminate at unique polyA sites. Within the context of the invention, the types of variants described herein are also preferred target nucleic acids.

The locations on the target nucleic acid to which preferred compounds and compositions of the invention hybridize are herein below referred to as “preferred target segments.” As used herein the term “preferred target segment” is defined as at least an 8-nucleobase portion of a target region to which an active antisense oligomeric compound is targeted. While not wishing to be bound by theory, it is presently believed that these target segments represent portions of the target nucleic acid that are accessible for hybridization.

Once one or more target regions, segments or sites have been identified, oligomeric compounds are chosen which are sufficiently complementary to the target, i.e., hybridize sufficiently well and with sufficient specificity, to give the desired effect.

In accordance with an embodiment of the this invention, a series of nucleic acid duplexes comprising the antisense strand oligomeric compounds of the present invention and their respective complement sense strand compounds can be designed for a specific target or targets. The ends of the strands may be modified by the addition of one or more natural or modified nucleobases to form an overhang. The sense strand of the duplex is designed and synthesized as the complement of the antisense strand and may also contain modifications or additions to either terminus. For example, in one embodiment, both strands of the duplex would be complementary over the central nucleobases, each having overhangs at one or both termini.

For the purposes of describing an embodiment of this invention, the combination of an antisense strand and a sense strand, each of can be of a specified length, for example from 18 to 29 nucleotides long, is identified as a complementary pair of siRNA oligonucleotides. This complementary pair of siRNA oligonucleotides can include additional nucleotides on either of their 5′ or 3′ ends. Further they can include other molecules or molecular structures on their 3′ or 5′ ends such as a phosphate group on the 5′ end. A preferred group of compounds of the invention include a phosphate group on the 5′ end of the antisense strand compound. Other preferred compounds also include a phosphate group on the 5′ end of the sense strand compound. Even further preferred compounds would include additional nucleotides such as a two base overhang on the 3′ end.

For example, a preferred siRNA complementary pair of oligonucleotides comprise an antisense strand oligomeric compound having the sequence CGAGAGGCGGACGGGACCG (SEQ ID NO:1) and having a two-nucleobase overhang of deoxythymidine(dT) and its complement sense strand. These oligonucleotides would have the following structure:

5′     c g a g a g g c g g a c g g g a c c g T T 3′ Antisense Strand (SEQ ID NO: 2)        | | | | | | | | | | | | | | | | | | | 3′ T T g c t c t c c g c c t g c c c t g g c     5′ Complement Strand (SEQ ID NO: 3)

In an additional embodiment of the invention, a single oligonucleotide having both the antisense portion as a first region in the oligonucleotide and the sense portion as a second region in the oligonucleotide is selected. The first and second regions are linked together by either a nucleotide linker (a string of one or more nucleotides that are linked together in a sequence) or by a non-nucleotide linker region or by a combination of both a nucleotide and non-nucleotide structure. In each of these structures, the oligonucleotide, when folded back on itself, would be complementary at least between the first region, the antisense portion, and the second region, the sense portion. Thus the oligonucleotide would have a palindrome within it structure wherein the first region, the antisense portion in the 5′ to 3′ direction, is complementary to the second region, the sense portion in the 3′ to 5′ direction.

In a further embodiment, the invention includes oligonucleotide/protein compositions. Such compositions have both an oligonucleotide component and a protein component. The oligonucleotide component comprises at least one oligonucleotide, either the antisense or the sense oligonucleotide but preferably the antisense oligonucleotide (the oligonucleotide that is antisense to the target nucleic acid). The oligonucleotide component can also comprise both the antisense and the sense strand oligonucleotides. The protein component of the composition comprises at least one protein that forms a portion of the RNA-induced silencing complex, i.e., the RISC complex.

RISC is a ribonucleoprotein complex that contains an oligonucleotide component and proteins of the Argonaute family of proteins, among others. While we do not wish to be bound by theory, the Argonaute proteins make up a highly conserved family whose members have been implicated in RNA interference and the regulation of related phenomena. Members of this family have been shown to possess the canonical PAZ and Piwi domains, thought to be a region of protein-protein interaction. Other proteins containing these domains have been shown to effect target cleavage, including the RNAse, Dicer. The Argonaute family of proteins includes, but depending on species, are not necessary limited to, elF2C1 and elF2C2. elF2C2 is also known as human GERp95. While we do not wish to be bound by theory, at least the antisense oligonucleotide strand is bound to the protein component of the RISC complex. Additionally, the complex might also include the sense strand oligonucleotide. Carmell et al, Genes and Development 2002, 16, 2733-2742.

Also, while we do not wish to be bound by theory, it is further believe that the RISC complex may interact with one or more of the translation machinery components. Translation machinery components include but are not limited to proteins that effect or aid in the translation of an RNA into protein including the ribosomes or polyribosome complex. Therefore, in a further embodiment of the invention, the oligonucleotide component of the invention is associated with a RISC protein component and further associates with the translation machinery of a cell. Such interaction with the translation machinery of the cell would include interaction with structural and enzymatic proteins of the translation machinery including but not limited to the polyribosome and ribosomal subunits.

In a further embodiment of the invention, the oligonucleotide of the invention is associated with cellular factors such as transporters or chaperones. These cellular factors can be protein, lipid or carbohydrate based and can have structural or enzymatic functions that may or may not require the complexation of one or more metal ions.

Furthermore, the oligonucleotide of the invention itself may have one or more moieties which are bound to the oligonucleotide which facilitate the active or passive transport, localization or compartmentalization of the oligonucleotide. Cellular localization includes, but is not limited to, localization to within the nucleus, the nucleolus or the cytoplasm. Compartmentalization includes, but is not limited to, any directed movement of the oligonucleotides of the invention to a cellular compartment including the nucleus, nucleolus, mitochondrion, or imbedding into a cellular membrane surrounding a compartment or the cell itself.

In a further embodiment of the invention, the oligonucleotide of the invention is associated with cellular factors that affect gene expression, more specifically those involved in RNA modifications. These modifications include, but are not limited to posttrascriptional modifications such as methylation. Furthermore, the oligonucleotide of the invention itself may have one or more moieties which are bound to the oligonucleotide which facilitate the posttranscriptional modification.

The oligomeric compounds of the invention may be used in the form of single-stranded, double-stranded, circular or hairpin oligomeric compounds and may contain structural elements such as internal or terminal bulges or loops. Once introduced to a system, the oligomeric compounds of the invention may interact with or elicit the action of one or more enzymes or may interact with one or more structural proteins to effect modification of the target nucleic acid.

One non-limiting example of such an interaction is the RISC complex. Use of the RISC complex to effect cleavage of RNA targets thereby greatly enhances the efficiency of oligonucleotide-mediated inhibition of gene expression. Similar roles have been postulated for other ribonucleases such as those in the RNase III and ribonuclease L family of enzymes.

Preferred forms of oligomeric compound of the invention include a single-stranded antisense oligonucleotide that binds in a RISC complex, a double stranded antisense/sense pair of oligonucleotide or a single strand oligonucleotide that includes both an antisense portion and a sense portion. Each of these compounds or compositions is used to induce potent and specific modulation of gene function. Such specific modulation of gene function has been shown in many species by the introduction of double-stranded structures, such as double-stranded RNA (dsRNA) molecules and has been shown to induce potent and specific antisense-mediated reduction of the function of a gene or its associated gene products. This phenomenon occurs in both plants and animals and is believed to have an evolutionary connection to viral defense and transposon silencing.

The compounds and compositions of the invention are used to modulate the expression of a target nucleic acid. “Modulators” are those oligomeric compounds that decrease or increase the expression of a nucleic acid molecule encoding a target and which comprise at least an 8-nucleobase portion that is complementary to a preferred target segment. The screening method comprises the steps of contacting a preferred target segment of a nucleic acid molecule encoding a target with one or more candidate modulators, and selecting for one or more candidate modulators which decrease or increase the expression of a nucleic acid molecule encoding a target. Once it is shown that the candidate modulator or modulators are capable of modulating (e.g. either decreasing or increasing) the expression of a nucleic acid molecule encoding a target, the modulator may then be employed in further investigative studies of the function of a target, or for use as a research, diagnostic, or therapeutic agent in accordance with the present invention.

Oligomeric Compounds

In the context of the present invention, the term “oligomeric compound” refers to a polymeric structure capable of hybridizing a region of a nucleic acid molecule. This term includes oligonucleotides, oligonucleosides, oligonucleotide analogs, oligonucleotide mimetics and combinations of these. Oligomeric compounds are routinely prepared linearly but can be joined or otherwise prepared to be circular, and may also include branching. Oligomeric compounds can hybridized to form double stranded compounds that can be blunt ended or may include overhangs. In general an oligomeric compound comprises a backbone of linked momeric subunits where each linked momeric subunit is directly or indirectly attached to a heterocyclic base moiety. The linkages joining the monomeric subunits, the sugar moieties or surrogates and the heterocyclic base moieties can be independently modified giving rise to a plurality of motifs for the resulting oligomeric compounds including hemimers, gapmers and chimeras.

As is known in the art, a nucleoside is a base-sugar combination. The base portion of the nucleoside is normally a heterocyclic base moiety. The two most common classes of such heterocyclic bases are purines and pyrimidines. Nucleotides are nucleosides that further include a phosphate group covalently linked to the sugar portion of the nucleoside. For those nucleosides that include a pentofuranosyl sugar, the phosphate group can be linked to either the 2′, 3′ or 5′ hydroxyl moiety of the sugar. In forming oligonucleotides, the phosphate groups covalently link adjacent nucleosides to one another to form a linear polymeric compound. The respective ends of this linear polymeric structure can be joined to form a circular structure by hybridization or by formation of a covalent bond, however, open linear structures are generally preferred. Within the oligonucleotide structure, the phosphate groups are commonly referred to as forming the internucleoside linkages of the oligonucleotide. The normal internucleoside linkage of RNA and DNA is a 3′ to 5′ phosphodiester linkage.

In the context of this invention, the term “oligonucleotide” refers to an oligomer or polymer of ribonucleic acid (RNA) or deoxyribonucleic acid (DNA). This term includes oligonucleotides composed of naturally-occurring nucleobases, sugars and covalent internucleoside linkages. The term “oligonucleotide analog” refers to oligonucleotides that have one or more non-naturally occurring portions which function in a similar manner to oligonucleotides. Such non-naturally occurring oligonucleotides are often preferred over the naturally occurring forms because of desirable properties such as, for example, enhanced cellular uptake, enhanced affinity for nucleic acid target and increased stability in the presence of nucleases.

In the context of this invention, the term “oligonucleoside” refers to nucleosides that are joined by internucleoside linkages that do not have phosphorus atoms. Internucleoside linkages of this type include short chain alkyl, cycloalkyl, mixed heteroatom alkyl, mixed heteroatom cycloalkyl, one or more short chain heteroatomic and one or more short chain heterocyclic. These internucleoside linkages include but are not limited to siloxane, sulfide, sulfoxide, sulfone, acetyl, formacetyl, thioformacetyl, methylene formacetyl, thioformacetyl, alkenyl, sulfamate; methyleneimino, methylenehydrazino, sulfonate, sulfonamide, amide and others having mixed N, O, S and CH₂ component parts.

In addition to the modifications described above, the nucleosides of the oligomeric compounds of the invention can have a variety of other modifications so long as these other modifications either alone or in combination with other nucleosides enhance one or more of the desired properties described above. Thus, for nucleotides that are incorporated into oligonucleotides of the invention, these nucleotides can have sugar portions that correspond to naturally-occurring sugars or modified sugars. Representative modified sugars include carbocyclic or acyclic sugars, sugars having substituent groups at one or more of their 2′, 3′ or 4′ positions and sugars having substituents in place of one or more hydrogen atoms of the sugar. Additional nucleosides amenable to the present invention having altered base moieties and or altered sugar moieties are disclosed in U.S. Pat. No. 3,687,808 and PCT application PCT/US89/02323.

Altered base moieties or altered sugar moieties also include other modifications consistent with the spirit of this invention. Such oligonucleotides are best described as being structurally distinguishable from, yet functionally interchangeable with, naturally occurring or synthetic wild type oligonucleotides. All such oligonucleotides are comprehended by this invention so long as they function effectively to mimic the structure of a desired RNA or DNA strand. A class of representative base modifications include tricyclic cytosine analog, termed “G clamp” (Lin, et al., J. Am. Chem. Soc. 1998, 120, 8531). This analog makes four hydrogen bonds to a complementary guanine (G) within a helix by simultaneously recognizing the Watson-Crick and Hoogsteen faces of the targeted G. This G clamp modification when incorporated into phosphorothioate oligonucleotides, dramatically enhances antisense potencies in cell culture. The oligonucleotides of the invention also can include phenoxazine-substituted bases of the type disclosed by Flanagan, et al., Nat. Biotechnol. 1999, 17(1), 48-52.

The oligomeric compounds in accordance with this invention preferably comprise from about 8 to about 80 nucleobases (i.e. from about 8 to about 80 linked nucleosides and/or monomeric subunits). One of ordinary skill in the art will appreciate that the invention embodies oligomeric compounds of 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, or 80 nucleobases in length.

In one preferred embodiment, the oligomeric compounds of the invention are 10 to 50 nucleobases in length. One having ordinary skill in the art will appreciate that this embodies oligomeric compounds of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 nucleobases in length.

In another preferred embodiment, the oligomeric compounds of the invention are 12 to 30 nucleobases in length. One having ordinary skill in the art will appreciate that this embodies oligomeric compounds of 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 nucleobases in length.

In a further preferred embodiment, the oligomeric compounds of the invention are 12 to 24 nucleobases in length. One having ordinary skill in the art will appreciate that this embodies oligomeric compounds of 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 nucleobases in length.

In another preferred embodiment, the oligomeric compounds of the invention are 19 to 23 nucleobases in length. One having ordinary skill in the art will appreciate that this embodies oligomeric compounds of 19, 20, 21, 22 or 23 nucleobases in length.

One particularly preferred length for oligomeric compounds is from about 12 to about 30 nucleobases. Another particularly preferred length is from about 12 to about 24 nucleobases. A further particularly preferred length is from about 19 to about 23 nucleobases.

General Oligomer Synthesis

Oligomerization of modified and unmodified nucleosides is performed according to literature procedures for DNA-like compounds (Protocols for Oligonucleotides and Analogs, Ed. Agrawal (1993), Humana Press) and/or RNA like compounds (Scaringe, Methods (2001), 23, 206-217. Gait et al., Applications of Chemically synthesized RNA in RNA:Protein Interactions, Ed. Smith (1998), 1-36. Gallo et al., Tetrahedron (2001), 57, 5707-5713) synthesis as appropriate. In addition specific protocols for the synthesis of oligomeric compounds of the invention are illustrated in the examples below.

RNA oligomers can be synthesized by methods disclosed herein or purchased from various RNA synthesis companies such as for example Dharmacon Research Inc., (Lafayette, Colo.).

Irrespective of the particular protocol used, the oligomeric compounds used in accordance with this invention may be conveniently and routinely made through the well-known technique of solid phase synthesis. Equipment for such synthesis is sold by several vendors including, for example, Applied Biosystems (Foster City, Calif.). Any other means for such synthesis known in the art may additionally or alternatively be employed.

For double stranded structures of the invention, once synthesized, the complementary strands preferably are annealed. The single strands are aliquoted and diluted to a concentration of 50 uM. Once diluted, 30 uL of each strand is combined with 15 uL of a 5× solution of annealing buffer. The final concentration of the buffer is 100 mM potassium acetate, 30 mM HEPES-KOH pH 7.4, and 2 mM magnesium acetate. The final volume is 75 uL. This solution is incubated for 1 minute at 90° C. and then centrifuged for 15 seconds. The tube is allowed to sit for 1 hour at 37° C. at which time the dsRNA duplexes are used in experimentation. The final concentration of the dsRNA compound is 20 uM. This solution can be stored frozen (−20° C.) and freeze-thawed up to 5 times.

Once prepared, the desired synthetic duplexes are evaluated for their ability to modulate target expression. When cells reach 80% confluency, they are treated with synthetic duplexes comprising at least one oligomeric compound of the invention. For cells grown in 96-well plates, wells are washed once with 200 μL OPTI-MEM-1 reduced-serum medium (Gibco BRL) and then treated with 130 μL of OPTI-MEM-1 containing 12 μg/mL LIPOFECTIN (Gibco BRL) and the desired dsRNA compound at a final concentration of 200 nM. After 5 hours of treatment, the medium is replaced with fresh medium. Cells are harvested 16 hours after treatment, at which time RNA is isolated and target reduction measured by RT-PCR.

Oligomer and Monomer Modifications

As is known in the art, a nucleoside is a base-sugar combination. The base portion of the nucleoside is normally a heterocyclic base. The two most common classes of such heterocyclic bases are the purines and the pyrimidines. Nucleotides are nucleosides that further include a phosphate group covalently linked to the sugar portion of the nucleoside. For those nucleosides that include a pentofuranosyl sugar, the phosphate group can be linked to either the 2′, 3′ or 5′ hydroxyl moiety of the sugar. In forming oligonucleotides, the phosphate groups covalently link adjacent nucleosides to one another to form a linear polymeric compound. In turn, the respective ends of this linear polymeric compound can be further joined to form a circular compound, however, linear compounds are generally preferred. In addition, linear compounds may have internal nucleobase complementarity and may therefore fold in a manner as to produce a fully or partially double-stranded compound. Within oligonucleotides, the phosphate groups are commonly referred to as forming the internucleoside linkage or in conjunction with the sugar ring the backbone of the oligonucleotide. The normal internucleoside linkage that makes up the backbone of RNA and DNA is a 3′ to 5′ phosphodiester linkage.

Modified Internucleoside Linkages

Specific examples of preferred antisense oligomeric compounds useful in this invention include oligonucleotides containing modified e.g. non-naturally occurring internucleoside linkages. As defined in this specification, oligonucleotides having modified internucleoside linkages include internucleoside linkages that retain a phosphorus atom and internucleoside linkages that do not have a phosphorus atom. For the purposes of this specification, and as sometimes referenced in the art, modified oligonucleotides that do not have a phosphorus atom in their internucleoside backbone can also be considered to be oligonucleosides.

In the C. elegans system, modification of the internucleotide linkage (phosphorothioate) did not significantly interfere with RNAi activity. Based on this observation, it is suggested that certain preferred oligomeric compounds of the invention can also have one or more modified internucleoside linkages.

Phosphorothioates. In certain embodiments, the invention relates to oligonucleotides containing at least one phosphorothioate internucleoside linkage in which a non-bonding oxygen atom of a natural phosphodiester linkage is replaced with sulfur, as described, for example, in U.S. Pat. Nos. 3,687,808, 5,264,423, 5,276,019, 5,286,717, and 5,936,080 hereby incorporated by reference in their entireties.

In accordance with other aspects of the invention, oligonucleotides are provided that contain at least one region of alternating phosphodiester and phosphorothioate internucleoside likages, as described, for example, in U.S. Pat. Nos. 6,277,967 and 6,326,358, hereby incorporated herein by reference in their entireties. In some especially preferred embodiments, the region of alternating phosphodiester/phosphorothioate linkages occurs at at least one terminal of the oligonucleotide. It is especially preferred that the terminal nucleotide of such a region have a phosphorothioate linkage. In other embodiments, oligonucleotides are provided that contain alternating phosphorothioate and phosphodiester linkages or alternating phosphodiester and phosphorothioate linkages throughout the entire length of the oligonucleotides. Certain aspects of the invention also relate to oligonucleotides that contain only phosphorothioate linkages.

Phosphorodithioates. In other embodiments, the invention relates to oligonucleotides containing at least one phosphorodithioate internucleoside linkage, which is an internucleotide linkage having the general formula 5′-nucleoside-O—P(S)S—O-nucleoside-3′ or 5′-nucleoside-O—P(S)SH—O-nucleoside-3′ as described, for example, in U.S. Pat. Nos. 5,278,302, 5,453,496, and 5,750,666, hereby incorporated by reference in their entireties.

Phosphonates. In certain aspects, the invention is directed to oligonucleotides containing at least one phosphonate internucleoside linkage in which an a hydrogen atom or an alkyl or aryl group replaces one of the two non-bonding (or non-bridging) oxygens on the phosphorus of a phosphodiester internucleosidyl linkage, while the other non-bonding oxygen remains or is alternatively replaced by sulfur or selenium, as described, for example, in U.S. Pat. Nos. 4,469,863, 5,204,455, 5,789,576 and 5,986,083, hereby incorporated by reference in their entireties. In certain embodiments, the invention relates to oligonucleotides containing alkyl-, cyclohexyl-, benzyl-, and phenyl-phosphonate internucleoside linkages, as described, for example, in U.S. Pat. No. 5,789,576, hereby incorporated by reference in its entirety. In certain other embodiments, the invention provides oligonucleotides having mixed internucleosidyl linkages, that is, oligonucleotides having phosphonate internucleosidyl linkages interspersed with single non-phosphonate, internucleosidyl linkages. According to an especially preferred aspect, oligonucleotides are provided having methylphosphonate linkages which alternate with phosphodiester linkages.

In one aspect, the present invention is directed to oligonucleotides in which the phosphonate internucleoside linkages are of undefined chirality. Such phosphonate linkages of undefined chirality are termed “racemic phosphonate linkages”.

In certain other aspects, the invention relates to oligonucleotides containing at least one phosphonothioate internucleotide linkage, which is an internucleotide linkage having the general formula 5′-nucleoside-O—P(S)R—O-nucleoside-3′ where R is a hydrogen atom, or an alkyl or aryl group as described, for example, in U.S. Pat. No. 5,750,666, hereby incorporated by reference in its entirety.

Phosphotriesters. In certain embodiments of the invention, oligonucleotides are provided that contain at least one phosphotriester internucleoside linkage in which a non-bonding oxygen atom of a natural phosphodiester linkage is replaced with an alkoxy group as described, for example, in U.S. Pat. No. 5,023,243, hereby incorporated by reference in its entirety.

In accordance with other aspects of the invention, oligonucleotides are provide that contain at least one alkylphosphotriester internucleoside linkage in which the alkyl group includes, but is not limited to, methyl, ethyl, isopropyl, and propyl, as described, for example, in U.S. Pat. No. 6,015,886, hereby incorporated by reference in its entirety. In other embodiments, oligonucleotides are provided that contain at least one aminoalkylphosphotriester internucleoside linkage as described, for example, in U.S. Pat. Nos. 5,536,821, 5,541,306, and 5,563,253, hereby incorporated by reference in their entireties.

In certain other aspects, the invention relates to oligonucleotides containing at least one phosphorothiotriester internucleotide linkage, which is a phosphorothioate internucleoside linkage in which a non-bonding oxygen atom is replaced with an alkoxy group. In certain further embodiments, the invention relates to oligonucleotides containing at least one S-alkyl or S-arylphosphorothiotriester internucleotide linkage, which is an internucleotide linkage having the general formula 5′-nucleoside-O—P(O)SR—O-nucleoside-3′ wherein R is an alkyl or aryl group as described, for example, in U.S. Pat. No. 5,750,666, hereby incorporated by reference in its entirety.

In further aspects, the invention relates to oligonucleotides containing at least one O-alkyl or arylphosphorothiotriester internucleotide linkage, which is an internucleotide linkage having the general formula 5′-nucleoside-O—P(S)OR—O-nucleoside-3′ wherein R is an alkyl or aryl group as described, for example, in U.S. Pat. No. 5,750,666, hereby incorporated by reference in its entirety.

Phosphoroamidates. In accordance with certain other aspects, the invention relates to oligonucleotides containing at least one phosphoramidate intersubunit linkage in which a non-bonding oxygen atom of a natural phosphodiester linkage is replaced with an amine or substituted amine (including a heterocyclic amine), as described, for example, in U.S. Pat. Nos. 5,476,925, 5,726,297, 5,837,835, 5,591,584 and 5,965,720, hereby incorporated by reference in their entireties. In certain embodiments, the phosphoramidate linkage is a 3′aminophosphoramidate linkage as described, for example, in U.S. Pat. No. 5,476,925, hereby incorporated by reference in its entirety. In other embodiments, the phosphoramidate linkage is an aminoalkylphosphoramidate linkage as described, for example, in U.S. Pat. Nos. 5,519,126 and 5,536,821, hereby incorporated by reference in their entireties.

In one embodiment, the invention relates to oligonucleotides having at least three contiguous subunits joined by N3′→P5′ phosphoramidate linkages. This grouping of linkages can, for example, be located at the 3′ end of the oligodeoxyribonucleotide. In another embodiment of the present invention, all of the intersubunit linkages of the oligonucleotide are N3′→P5′ phosphoramidate linkages. Also included in the invention are oligonucleotides where the intersubunit linkages alternate between the N3′→P5′ phosphoramidate linkage and a second linkage. The second linkage can be selected from one or more different types of linkages, for example, phosphodiester linkages or phosphodiester and phosphorothioate linkages. The second linkage is selected, for example, from the group consisting of phosphodiester, phosphotriester, methylphosphonate, phosphoramidate P3′→N5′, and phosphorothioate. In one embodiment, at least 50% of the intersubunit linkages of the oligonucleotide are N3′→P5′ phosphoramidate linkages.

In certain other aspects, the invention relates to oligonucleotides containing at least one phosphorothioamidate internucleoside linkage, which is an internucleotide linkage having the general formula 5′-nucleoside-O—P(S)NHR—O-nucleoside-3′ or 5′-nucleoside-O—P(S)NR₁R₂—O-nucleoside-3′ as described, for example, in U.S. Pat. No. 5,750,666, hereby incorporated by reference in its entirety. In certain other embodiments, the phosphoramidate linkage is an aminoalkylphosphorthioamidate linkage as described, for example, in U.S. Pat. No. 5,536,821, hereby incorporated by reference in its entirety.

Phosphinates. In certain embodiments, the invention relates to oligonucleotides containing at least one phosphinate internucleoside linkage in which a hydrogen atom or an alkyl or aryl group replaces both of the non-bonding oxygens on the phosphorous of a phosphodiester internucleoside linkage, as described, for example, in U.S. Pat. No. 5,466,677, hereby incorporated by reference in its entirety.

Boronates. In certain other embodiments, the invention relates to oligonucleotides containing at least one boronate internucleoside phosphodiester linkage as described, for example, in U.S. Pat. No. 5,455,233, hereby incorporated by reference in its entirety. Such linkages, for example, are of the following formula:

wherein W is selected from the group consisting of ═O, ═S, ═OR′, ═SR′, and —OCH₂CH₂CH, wherein R′ is C1 to C3 alkyl. X is selected from the group consisting of —BH₃, —BH₂R₁, —BHR₁R₂ and —BR₁R₂R₃. R₁ is selected from the group consisting of —R₄, —COOH, —COOR₄, —CONHR₄, —CON(R₄)₂, —CN⁺R₄Z⁻, wherein Z⁻ is an anion, —CN, carboxycholesteryl and carboxybenzyl, wherein R₄ is C1 to C18 alkyl. R₂ is selected from the group consisting of —R₅, —COOH, —COOR₅, —CONHR₅, —CON(R₅)₂, —CN⁺R₅Z⁻, wherein Z⁻ is an anion, —CN, carboxy-cholesteryl and carboxybenzyl, wherein R₅ is C1 to C18 alkyl. R₃ is selected from the group consisting of C1 to C3 alkyl. Most preferably, X is —BH₃ and W is =0.

alpha-D-arabinofuranosyl. In certain other aspects, the invention relates to oligonucleotides formed from α-D-arabinofuranosyl nucleoside monomers, including oligonucleotides in which one or more of the monomer units is functionalized as described, for example, in U.S. Pat. No. 5,177,196, hereby incorporated by reference in its entirety. A generic formula for such an oligonucleotide is, for example:

in which B is a nucleotide base which will vary from one monomeric unit to the next in a preselected oligonucleotide sequence; R is phosphate, phosphorothioate, phosphoramidate, or alkanephosphonate; t is 1 for functionalized monomeric units and zero for the others; W is a chemical linker arm; A is a functional group; and n is the number of monomeric units in the oligomer.

2′-5′. In other embodiments, the invention relates to oligonucleotides containing 2′-5′ linkages, such as, for example, 2′-5′ oligoadenylates as described in U.S. Pat. Nos. 5,583,032, 5,677,289, 5,700,785, and 6,281,201, hereby incorporated by reference in their entireties. As used herein, the term “2′-5′ oligoadenylate” refers to oligonucleotides made up of adenosines that are linked at their 2′ and 5′ carbons through phosphodiester bonds to other adenosine molecules.

In certain embodiments, the invention relates to 2′-5′-oligoadenylates wherein the internucleotide phosphodiester linkages are replaced with optically active phosphorothioate groups, as described, for example, in U.S. Pat. Nos. 4,924,624, 5,188,897, 5,405,939, 5,550,111, 5,556,840, 5,643,889, and 6,281,201 hereby incorporated by reference in their entireties. According to certain aspects of the invention, at least one of the internucleotide phosphorothioate 2′-5′-linkages is of the Sp configuration.

In other aspects, the invention provides 2′-5′ linked oligonucleotides containing substitution of either or both of the bridging 5′ and 2′ oxygen atoms of the phosphate backbone by different heteroatom(s) which include, but are not limited to, hydrogen, alkyl, allyl or an aryl group of from one to about twenty carbons as described, for example, in U.S. Pat. No. 5,532,130, hereby incorporated by reference in its entirety.

In certain embodiments of the invention, oligonucleotides containing 2′-5′ xyloadenosine internucleoside linkages are provided as described, for example, in U.S. Pat. No. 4,476,301, hereby incorporated by reference in its entirety. Xyloadenosine designates the compound constituted by xylose linked to adenine in which the xylose is in either the furan or pyrane form.

In certain other embodiments, the invention relates to 2′-5′ oligoadenylate analogues such as, for example, (2′-5′)oligoadenylates containing 9-(2,3-anhydro-β-D-ribofuranosyl)adenine (2′-5′)A₂A_(r-epoxy) and 9-(2,3-anhydro-β-D-lyxofuranosyl)adenine (2′-5′)A₂A_(1-epoxy) as described, for example, in U.S. Pat. No. 5,571,799, hereby incorporated by reference in its entirety.

In certain other embodiments, the invention relates to oligonucleotides containing 2′-5′ internucleoside linkages of the following formulas:

wherein

-   -   X is O or S;     -   Y is O or S;     -   R is H, OH, or OCH₃;     -   B is adenine, guanine, cytosine, uracil, 5-methyl uracil, or         5-methyl cytosine; or

wherein

-   -   X is O or S;     -   Y is O or S;     -   R is O—CH₂—CH₂—NH—C(NH)NH₂ or O—CH₂—CH₂—N(CH₃)₂;     -   B is adenine, guanine, cytosine, uracil, 5-methyl uracil, or         5-methyl cytosine.         Oligonucleotides of the above formulas can be synthesized, for         example, as described in Examples 17 and 18.

Inverted polarity. In certain aspects of the invention, inverted polarity oligonucleotides are provided as described, for example, in U.S. Pat. No. 5,399,676, hereby incorporated by reference in its entirety. Inverted polarity oligonucleotides contain at least one segment along their length of one of the following formulas: 3′- - - 5′- -C - -5′- - - 3′  (1) or 5′- - - 3′- -C - -3′- - - 5′  (2) where --C-- symbolizes any method of coupling the nucleotide sequences of opposite polarity. In these formulas, the symbol 3′- - - 5′ indicates a stretch of oligomer in which the linkages are consistently formed between the 5′ hydroxyl of the ribosyl residue of the nucleotide to the left with the 3′ hydroxyl of the ribosyl residue of the nucleotide to the right, thus leaving the 5′ hydroxyl of the rightmost nucleotide ribosyl residue free for additional conjugation. Analogously, 5′- - - 3′ indicates a stretch of oligomer in the opposite orientation wherein the linkages are formed between the 3′ hydroxyl of the ribosyl residue of the left nucleotide and the 5′ hydroxyl of the ribosyl residue of the nucleotide on the right, thus leaving the 3′ hydroxyl of the rightmost nucleotide ribosyl residue free for additional conjugation. The linkage, symbolized by --C--, may be formed so as to link the 5′ hydroxyls of the adjacent ribosyl residues in formula (1) or the 3′ hydroxyls of the adjacent ribosyl residues in formula (2), or the “--C--” linkage may conjugate other portions of the adjacent nucleotides so as to link the inverted polarity strands. “--C--” may represent a linker moiety, or simply a covalent bond. It should be noted that if the linkage between strands of inverted polarity involves a sugar residue, either the 3′ or 2′ position can be involved in the linkage.

In addition to the use of standard oligonucleotide synthesis techniques or other couplings to effect the 5′--5′ or 3′--3′ linkage between ribosyl moieties, alternative approaches to joining the two strands of inverted polarity may be employed. For example, the two appended bases of the opposing termini of the inverted polarity oligonucleotide sequences can be linked directly or through a linker, or the base of one can be linked to the sugar moiety of the other. Any suitable method of effecting the linkage may be employed. Depending on the manner of coupling the segments with inverted polarity, this coupling may be effected by insertion of a dimeric nucleotide wherein the appropriate 3′ positions of each member of the dimer or the 5′ positions of each member of the dimer are activated for inclusion of the dimer in the growing chain, or the conventional synthesis can be continued but using for the condensing nucleotide a nucleotide which is protected/activated in the inverse manner to that which would be employed if the polarity of the chain were to remain the same. This additional nucleotide may also contain a linker moiety that may be included before or after condensation to extend the chain.

Chirally Pure. In accordance with certain aspects of this invention, oligonucleotides are provided that contain substantially chirally pure phosphorous-containing internucleoside linkages such as, for example, chirally pure phosphorothioate linkages, as described, for example, in U.S. Pat. Nos. 5,506,212; 5,576,302; 5,587,361; 5,599,797; 5,607,923; 5,634,488; 5,661,134; and 5,582,188, hereby incorporated by reference in their entireties. Oligonucleotides wherein substantially all of the phosphorous atoms in the sugar backbone are either Sp or Rp are referred to herein as chirally pure. In accordance with other aspects of the invention, oligonucleotides are provided that comprise chirally pure alkylphosphonate, phosphotriester, phosphodiesterthioester, or phosphoramidate internucleoside linkages as described, for example, in U.S. Pat. Nos. 5,945,521 and 6,239,265, hereby incorporated by reference in their entireties. Oligonucleotides are provided, for example, having substantially pure chiral Sp phosphorothioate, chiral Rp phosphorothioate, chiral Sp alkylphosphonate, chiral Rp alkylphosphonate, chiral Sp phosphoamidate, chiral Rp phosphoamidate, chiral Sp phosphotriester, and chiral Rp phosphotriester linkages.

In another aspect, the invention relates to chirally pure phosphonate linkages, as described, for example, in U.S. Pat. Nos. 6,028,188 and 5,936,080, hereby incorporated by reference in their entireties. According to an especially preferred aspect, Rp-enriched oligonucleotides are provided having chirally pure Rp-methyl phosphonate linkages which alternate with phosphodiester linkages.

The oligonucleotides are prepared via a stereospecific SN₂ nucleophilic attack of a phosphodiester, phosphorothioate, phosphoramidate, phosphotriester or alkylphosphonate anion on the 3′ position of a xylonucleotide. The reaction proceeds via inversion at the 3′ position of the xylo reactant species, resulting in the incorporation of phosphodiester, phosphorothioate, phosphoramidate, phosphotriester or alkylphosphonate linked ribofuranosyl sugar moieties into the oligonucleotide.

In certain embodiments of the invention, oligomeric compounds are provided that have a first 5′-region that has at least one chiral Sp internucleoside linkage, and a second region that has chiral Rp internucleoside linkages, racemic phosphorothioate internucleoside linkages or internucleoside linkages other than chiral or racemic phosphorothioate internucleoside linkages. The present invention further provides oligomeric compounds having 3 regions where the first and second are as described above, and the third region has one or more Sp phosphorothioate internucleoside linkages, as described, for example, in U.S. Pat. No. 6,440,943, hereby incorporated by reference in its entirety.

Preferred modified oligonucleotide backbones that do not include a phosphorus atom therein have backbones that are formed by short chain alkyl or cycloalkyl internucleoside linkages, mixed heteroatom and alkyl or cycloalkyl internucleoside linkages, or one or more short chain heteroatomic or heterocyclic internucleoside linkages. These include those having morpholino linkages (formed in part from the sugar portion of a nucleoside); siloxane backbones; sulfide, sulfoxide and sulfone backbones; formacetyl and thioformacetyl backbones; methylene formacetyl and thioformacetyl backbones; riboacetyl backbones; alkene containing backbones; sulfamate backbones; methyleneimino and methylenehydrazino backbones; sulfonate and sulfonamide backbones; amide backbones; and others having mixed N, O, S and CH₂ component parts.

Representative United States patents that teach the preparation of the above oligonucleosides include, but are not limited to, U.S. Pat. Nos. 5,034,506; 5,166,315; 5,185,444; 5,214,134; 5,216,141; 5,235,033; 5,264,562; 5,264,564; 5,405,938; 5,434,257; 5,466,677; 5,470,967; 5,489,677; 5,541,307; 5,561,225; 5,596,086; 5,602,240; 5,610,289; 5,602,240; 5,608,046; 5,610,289; 5,618,704; 5,623,070; 5,663,312; 5,633,360; 5,677,437; 5,792,608; 5,646,269 and 5,677,439, certain of which are commonly owned with this application, and each of which is herein incorporated by reference.

Oligomer Mimetics

Another preferred group of oligomeric compounds amenable to the present invention includes oligonucleotide mimetics. The term mimetic as it is applied to oligonucleotides is intended to include oligomeric compounds wherein only the furanose ring or both the furanose ring and the internucleotide linkage are replaced with novel groups, replacement of only the furanose ring is also referred to in the art as being a sugar surrogate. The heterocyclic base moiety or a modified heterocyclic base moiety is maintained for hybridization with an appropriate target nucleic acid. One such oligomeric compound, an oligonucleotide mimetic that has been shown to have excellent hybridization properties, is referred to as a peptide nucleic acid (PNA). In PNA oligomeric compounds, the sugar-backbone of an oligonucleotide is replaced with an amide containing backbone, in particular an aminoethylglycine backbone. The nucleobases are retained and are bound directly or indirectly to aza nitrogen atoms of the amide portion of the backbone. Representative United States patents that teach the preparation of PNA oligomeric compounds include, but are not limited to, U.S. Pat. Nos. 5,539,082; 5,714,331; and 5,719,262, each of which is herein incorporated by reference. Further teaching of PNA oligomeric compounds can be found in Nielsen et al., Science, 1991, 254, 1497-1500.

One oligonucleotide mimetic that has been reported to have excellent hybridization properties is peptide nucleic acids (PNA). The backbone in PNA compounds is two or more linked aminoethylglycine units which gives PNA an amide containing backbone. The heterocyclic base moieties are bound directly or indirectly to aza nitrogen atoms of the amide portion of the backbone. Representative United States patents that teach the preparation of PNA compounds include, but are not limited to, U.S. Pat. Nos. 5,539,082; 5,714,331; and 5,719,262, each of which is herein incorporated by reference. Further teaching of PNA compounds can be found in Nielsen et al., Science, 1991, 254, 1497-1500.

PNA has been modified to incorporate numerous modifications since the basic PNA structure was first prepared. The basic structure is shown below:

wherein

-   -   Bx is a heterocyclic base moiety;     -   T₄ is hydrogen, an amino protecting group, —C(O)R₅, substituted         or unsubstituted C₁-C₁₀ alkyl, substituted or unsubstituted         C₂—C₁₀ alkenyl, substituted or unsubstituted C₂—C₁₀ alkynyl,         alkylsulfonyl, arylsulfonyl, a chemical functional group, a         reporter group, a conjugate group, a D or L α-amino acid linked         via the α-carboxyl group or optionally through the ω-carboxyl         group when the amino acid is aspartic acid or glutamic acid or a         peptide derived from D, L or mixed D and L amino acids linked         through a carboxyl group, wherein the substituent groups are         selected from hydroxyl, amino, alkoxy, carboxy, benzyl, phenyl,         nitro, thiol, thioalkoxy, halogen, alkyl, aryl, alkenyl and         alkynyl;     -   T₅ is —OH, —N(Z₁)Z₂, R₅, D or L α-amino acid linked via the         α-amino group or optionally through the ω-amino group when the         amino acid is lysine or ornithine or a peptide derived from D, L         or mixed D and L amino acids linked through an amino group, a         chemical functional group, a reporter group or a conjugate         group;     -   Z₁ is hydrogen, C₁-C₆ alkyl, or an amino protecting group;     -   Z₂ is hydrogen, C₁-C₆ alkyl, an amino protecting group,         —C(═O)—(CH₂)_(n)-J-Z₃, a D or L α-amino acid linked via the         α-carboxyl group or optionally through the ω-carboxyl group when         the amino acid is aspartic acid or glutamic acid or a peptide         derived from D, L or mixed D and L amino acids linked through a         carboxyl group;     -   Z₃ is hydrogen, an amino protecting group, —C₁-C₆ alkyl,         —C(═O)—CH₃, benzyl, benzoyl, or —(CH₂)_(n)—N(H)Z₁;     -   each J is O, S or NH;     -   R₅ is a carbonyl protecting group; and     -   n is from 2 to about 50.

Another class of oligonucleotide mimetic that has been studied is based on linked morpholino units (morpholino nucleic acid) having heterocyclic bases attached to the morpholino ring. A number of linking groups have been reported that link the morpholino monomeric units in a morpholino nucleic acid. A preferred class of linking groups have been selected to give a non-ionic oligomeric compound. The non-ionic morpholino-based oligomeric compounds are less likely to have undesired interactions with cellular proteins. Morpholino-based oligomeric compounds are non-ionic mimics of oligonucleotides which are less likely to form undesired interactions with cellular proteins (Dwaine A. Braasch and David R. Corey, Biochemistry, 2002, 41(14), 4503-4510). Morpholino-based oligomeric compounds are disclosed in U.S. Pat. No. 5,034,506, issued Jul. 23, 1991. The morpholino class of oligomeric compounds have been prepared having a variety of different linking groups joining the monomeric subunits.

Morpholino nucleic acids have been prepared having a variety of different linking groups (L₂) joining the monomeric subunits. The basic formula is shown below:

wherein

-   -   T₁ is hydroxyl or a protected hydroxyl;     -   T₅ is hydrogen or a phosphate or phosphate derivative;     -   L₂ is a linking group; and     -   n is from 2 to about 50.

A further class of oligonucleotide mimetic is referred to as cyclohexenyl nucleic acids (CeNA). The furanose ring normally present in an DNA/RNA molecule is replaced with a cyclohenyl ring. CeNA DMT protected phosphoramidite monomers have been prepared and used for oligomeric compound synthesis following classical phosphoramidite chemistry. Fully modified CeNA oligomeric compounds and oligonucleotides having specific positions modified with CeNA have been prepared and studied (see Wang et al., J. Am. Chem. Soc., 2000, 122, 8595-8602). In general the incorporation of CeNA monomers into a DNA chain increases its stability of a DNA/RNA hybrid. CeNA oligoadenylates formed complexes with RNA and DNA complements with similar stability to the native complexes. The study of incorporating CeNA structures into natural nucleic acid structures was shown by NMR and circular dichroism to proceed with easy conformational adaptation. Furthermore the incorporation of CeNA into a sequence targeting RNA was stable to serum and able to activate E. Coli RNase resulting in cleavage of the target RNA strand.

The general formula of CeNA is shown below:

wherein

-   -   each Bx is a heterocyclic base moiety;     -   T₁ is hydroxyl or a protected hydroxyl; and     -   T2 is hydroxyl or a protected hydroxyl.

Another class of oligonucleotide mimetic (anhydrohexitol nucleic acid) can be prepared from one or more anhydrohexitol nucleosides (see, Wouters and Herdewijn, Bioorg. Med. Chem. Lett., 1999, 9, 1563-1566) and would have the general formula:

A further preferred modification includes Locked Nucleic Acids (LNAs) in which the 2′-hydroxyl group is linked to the 4′ carbon atom of the sugar ring thereby forming a 2′-C,4′-C-oxymethylene linkage thereby forming a bicyclic sugar moiety. The linkage is preferably a methylene (—CH₂—)_(n) group bridging the 2′ oxygen atom and the 4′ carbon atom wherein n is 1 or 2 (Singh et al., Chem. Commun., 1998, 4, 455-456). LNA and LNA analogs display very high duplex thermal stabilities with complementary DNA and RNA (Tm=+3 to +10 C), stability towards 3′-exonucleolytic degradation and good solubility properties. The basic structure of LNA showing the bicyclic ring system is shown below:

The conformations of LNAs determined by 2D NMR spectroscopy have shown that the locked orientation of the LNA nucleotides, both in single-stranded LNA and in duplexes, constrains the phosphate backbone in such a way as to introduce a higher population of the N-type conformation (Petersen et al., J. Mol. Recognit., 2000, 13, 44-53). These conformations are associated with improved stacking of the nucleobases (Wengel et al., Nucleosides Nucleotides, 1999, 18, 1365-1370).

LNA has been shown to form exceedingly stable LNA:LNA duplexes (Koshkin et al., J. Am. Chem. Soc., 1998, 120, 13252-13253). LNA:LNA hybridization was shown to be the most thermally stable nucleic acid type duplex system, and the RNA-mimicking character of LNA was established at the duplex level. Introduction of 3 LNA monomers (T or A) significantly increased melting points (Tm=+15/+11) toward DNA complements. The universality of LNA-mediated hybridization has been stressed by the formation of exceedingly stable LNA:LNA duplexes. The RNA-mimicking of LNA was reflected with regard to the N-type conformational restriction of the monomers and to the secondary structure of the LNA:RNA duplex.

LNAs also form duplexes with complementary DNA, RNA or LNA with high thermal affinities. Circular dichroism (CD) spectra show that duplexes involving fully modified LNA (esp. LNA:RNA) structurally resemble an A-form RNA:RNA duplex. Nuclear magnetic resonance (NMR) examination of an LNA:DNA duplex confirmed the 3′-endo conformation of an LNA monomer. Recognition of double-stranded DNA has also been demonstrated suggesting strand invasion by LNA. Studies of mismatched sequences show that LNAs obey the Watson-Crick base pairing rules with generally improved selectivity compared to the corresponding unmodified reference strands.

Novel types of LNA-oligomeric compounds, as well as the LNAs, are useful in a wide range of diagnostic and therapeutic applications. Among these are antisense applications, PCR applications, strand-displacement oligomers, substrates for nucleic acid polymerases and generally as nucleotide based drugs.

Potent and nontoxic antisense oligonucleotides containing LNAs have been described (Wahlestedt et al., Proc. Natl. Acad. Sci. U.S.A, 2000, 97, 5633-5638.) The authors have demonstrated that LNAs confer several desired properties to antisense agents. LNA/DNA copolymers were not degraded readily in blood serum and cell extracts. LNA/DNA copolymers exhibited potent antisense activity in assay systems as disparate as G-protein-coupled receptor signaling in living rat brain and detection of reporter genes in Escherichia coli. Lipofectin-mediated efficient delivery of LNA into living human breast cancer cells has also been accomplished.

The synthesis and preparation of the LNA monomers adenine, cytosine, guanine, 5-methyl-cytosine, thymine and uracil, along with their oligomerization, and nucleic acid recognition properties have been described (Koshkin et al., Tetrahedron, 1998, 54, 3607-3630). LNAs and preparation thereof are also described in WO 98/39352 and WO 99/14226.

The first analogs of LNA, phosphorothioate-LNA and 2′-thio-LNAs, have also been prepared (Kumar et al., Bioorg. Med. Chem. Lett., 1998, 8, 2219-2222). Preparation of locked nucleoside analogs containing oligodeoxyribonucleotide duplexes as substrates for nucleic acid polymerases has also been described (Wengel et al., PCT International Application WO 98-DK393 19980914). Furthermore, synthesis of 2′-amino-LNA, a novel conformationally restricted high-affinity oligonucleotide analog with a handle has been described in the art (Singh et al., J. Org. Chem., 1998, 63, 10035-10039). In addition, 2′-Amino- and 2′-methylamino-LNA's have been prepared and the thermal stability of their duplexes with complementary RNA and DNA strands has been previously reported.

Further oligonucleotide mimetics have been prepared to include bicyclic and tricyclic nucleoside analogs having the formulas (amidite monomers shown):

(see Steffens et al., Helv. Chim. Acta, 1997, 80, 2426-2439; Steffens et al., J. Am. Chem. Soc., 1999, 121, 3249-3255; and Renneberg et al., J. Am. Chem. Soc., 2002, 124, 5993-6002). These modified nucleoside analogs have been oligomerized using the phosphoramidite approach and the resulting oligomeric compounds containing tricyclic nucleoside analogs have shown increased thermal stabilities (Tm's) when hybridized to DNA, RNA and itself. Oligomeric compounds containing bicyclic nucleoside analogs have shown thermal stabilities approaching that of DNA duplexes.

Another class of oligonucleotide mimetic is referred to as phosphonomonoester nucleic acids incorporate a phosphorus group in a backbone the backbone. This class of olignucleotide mimetic is reported to have useful physical and biological and pharmacological properties in the areas of inhibiting gene expression (antisense oligonucleotides, ribozymes, sense oligonucleotides and triplex-forming oligonucleotides), as probes for the detection of nucleic acids and as auxiliaries for use in molecular biology.

The general formula (for definitions of variables see: U.S. Pat. Nos. 5,874,553 and 6,127,346 herein incorporated by reference in their entirety) is shown below.

Another oligonucleotide mimetic has been reported wherein the furanosyl ring has been replaced by a cyclobutyl moiety.

Modified Sugars

Oligomeric compounds of the invention may also contain one or more substituted sugar moieties. Preferred oligomeric compounds comprise a sugar substituent group selected from: OH; F; O-, S-, or N-alkyl; O-, S-, or N-alkenyl; O-, S- or N-alkynyl; or O-alkyl-O-alkyl, wherein the alkyl, alkenyl and alkynyl may be substituted or unsubstituted C₁ to C₁₀ alkyl or C₂ to C₁₀ alkenyl and alkynyl. Particularly preferred are O[(CH₂)_(n)O]_(m)CH₃, O(CH₂)_(n)OCH₃, O(CH₂)_(n)NH₂, O(CH₂)_(n)CH₃, O(CH₂)_(n)ONH₂, and O(CH₂)_(n)ON[(CH₂)_(n)CH₃]₂, where n and m are from 1 to about 10. Other preferred oligonucleotides comprise a sugar substituent group selected from: C₁ to C₁₀ lower alkyl, substituted lower alkyl, alkenyl, alkynyl, alkaryl, aralkyl, O-alkaryl or O-aralkyl, SH, SCH₃, OCN, Cl, Br, CN, CF₃, OCF₃, SOCH₃, SO₂CH₃, ONO₂, NO₂, N₃, NH₂, heterocycloalkyl, heterocycloalkaryl, aminoalkylamino, polyalkylamino, substituted silyl, an RNA cleaving group, a reporter group, an intercalator, a group for improving the pharmacokinetic properties of an oligonucleotide, or a group for improving the pharmacodynamic properties of an oligonucleotide, and other substituents having similar properties. A preferred modification includes 2′-methoxyethoxy (2′-O—CH₂CH₂OCH₃, also known as 2′-O-(2-methoxyethyl) or 2′-MOE) (Martin et al., Helv. Chim. Acta, 1995, 78, 486-504) i.e., an alkoxyalkoxy group. A further preferred modification includes 2′-dimethylaminooxyethoxy, i.e., a O(CH₂)₂ON(CH₃)₂ group, also known as 2′-DMAOE, as described in examples hereinbelow, and 2′-dimethylaminoethoxyethoxy (also known in the art as 2′-O-dimethyl-amino-ethoxy-ethyl or 2′-DMAEOE), i.e., 2′-O—CH₂—O—CH₂—N(CH₃)₂.

Other preferred sugar substituent groups include methoxy (—O—CH₃), aminopropoxy (—OCH₂CH₂CH₂NH₂), allyl (—CH₂—CH═CH₂), —O-allyl (-O—CH₂—CH═CH₂) and fluoro (F). 2′-Sugar substituent groups may be in the arabino (up) position or ribo (down) position. A preferred 2′-arabino modification is 2′-F. Similar modifications may also be made at other positions on the oligomeric compound, particularly the 3′ position of the sugar on the 3′ terminal nucleoside or in 2′-5′ linked oligonucleotides and the 5′ position of 5′ terminal nucleotide. Oligomeric compounds may also have sugar mimetics such as cyclobutyl moieties in place of the pentofuranosyl sugar. Representative United States patents that teach the preparation of such modified sugar structures include, but are not limited to, U.S. Pat. Nos. 4,981,957; 5,118,800; 5,319,080; 5,359,044; 5,393,878; 5,446,137; 5,466,786; 5,514,785; 5,519,134; 5,567,811; 5,576,427; 5,591,722; 5,597,909; 5,610,300; 5,627,053; 5,639,873; 5,646,265; 5,658,873; 5,670,633; 5,792,747; and 5,700,920, certain of which are commonly owned with the instant application, and each of which is herein incorporated by reference in its entirety.

Further representative sugar substituent groups include groups of formula I_(a) or II_(a):

wherein:

-   -   R_(b) is O, S or NH;     -   R_(d) is a single bond, O, S or C(═O);     -   R_(e) is C₁-C₁₀ alkyl, N(R_(k))(R_(m)), N(R_(k))(R_(n)),         N═C(R_(p))(R_(q)), N═C(R_(p))(R_(r)) or has formula III_(a);

-   -   R_(p) and R_(q) are each independently hydrogen or C₁-C₁₀ alkyl;     -   R_(r) is —R_(x)—R_(y);     -   each R_(s), R_(t), R_(u) and R_(v) is, independently, hydrogen,         C(O)R_(w), substituted or unsubstituted C₁-C₁₀ alkyl,         substituted or unsubstituted C₂-C₁₀ alkenyl, substituted or         unsubstituted C₂-C₁₀ alkynyl, alkylsulfonyl, arylsulfonyl, a         chemical functional group or a conjugate group, wherein the         substituent groups are selected from hydroxyl, amino, alkoxy,         carboxy, benzyl, phenyl, nitro, thiol, thioalkoxy, halogen,         alkyl, aryl, alkenyl and alkynyl;     -   or optionally, R_(u) and R_(v), together form a phthalimido         moiety with the nitrogen atom to which they are attached;     -   each R_(w) is, independently, substituted or unsubstituted         C₁-C₁₀ alkyl, trifluoromethyl, cyanoethyloxy, methoxy, ethoxy,         t-butoxy, allyloxy, 9-fluorenylmethoxy,         2-(trimethylsilyl)-ethoxy, 2,2,2-trichloroethoxy, benzyloxy,         butyryl, iso-butyryl, phenyl or aryl;     -   R_(k) is hydrogen, a nitrogen protecting group or —R_(x)—R_(y);     -   R_(p) is hydrogen, a nitrogen protecting group or —R_(x)—R_(y);     -   R_(x) is a bond or a linking moiety;     -   R_(y) is a chemical functional group, a conjugate group or a         solid support medium;     -   each R_(m) and R_(n) is, independently, H, a nitrogen protecting         group, substituted or unsubstituted C₁-C₁₀ alkyl, substituted or         unsubstituted C₂-C₁₀ alkenyl, substituted or unsubstituted         C₂-C₁₀ alkynyl, wherein the substituent groups are selected from         hydroxyl, amino, alkoxy, carboxy, benzyl, phenyl, nitro, thiol,         thioalkoxy, halogen, alkyl, aryl, alkenyl, alkynyl; NH₃ ⁺,         N(R_(u))(R_(v)), guanidino and acyl where said acyl is an acid         amide or an ester;     -   or R_(m) and R_(n), together, are a nitrogen protecting group,         are joined in a ring structure that optionally includes an         additional heteroatom selected from N and O or are a chemical         functional group;     -   R_(i) is OR_(z), SR_(z), or N(R_(z))₂;     -   each R_(z) is, independently, H, C₁-C₈ alkyl, C₁-C₈ haloalkyl,         C(═NH)N(H)R_(u), C(═O)N(H)R_(u) or OC(═O)N(H)R_(u);     -   R_(f), R_(g) and R_(h) comprise a ring system having from about         4 to about 7 carbon atoms or having from about 3 to about 6         carbon atoms and 1 or 2 heteroatoms wherein said heteroatoms are         selected from oxygen, nitrogen and sulfur and wherein said ring         system is aliphatic, unsaturated aliphatic, aromatic, or         saturated or unsaturated heterocyclic;     -   R_(j) is alkyl or haloalkyl having 1 to about 10 carbon atoms,         alkenyl having 2 to about 10 carbon atoms, alkynyl having 2 to         about 10 carbon atoms, aryl having 6 to about 14 carbon atoms,         N(R_(k))(R_(m)) OR_(k), halo, SR_(k) or CN;     -   m_(a) is 1 to about 10;     -   each mb is, independently, 0 or 1;     -   mc is 0 or an integer from 1 to 10;     -   md is an integer from 1 to 10;     -   me is from 0, 1 or 2; and     -   provided that when mc is 0, md is greater than 1.

Representative substituents groups of Formula I are disclosed in U.S. patent application Ser. No. 09/130,973, filed Aug. 7, 1998, entitled “Capped 2′-Oxyethoxy Oligonucleotides,” hereby incorporated by reference in its entirety.

Representative cyclic substituent groups of Formula II are disclosed in U.S. patent application Ser. No. 09/123,108, filed Jul. 27, 1998, entitled “RNA Targeted 2′-Oligomeric compounds that are Conformationally Preorganized,” hereby incorporated by reference in its entirety.

Particularly preferred sugar substituent groups include O[(CH₂)_(n)O]_(m)CH₃, O(CH₂)_(n)OCH₃, O(CH₂)_(n)NH₂, O(CH₂)_(n)CH₃, O(CH₂)_(n)ONH₂, and O(CH₂)_(n)ON[(CH₂)_(n)CH₃)]₂, where n and m are from 1 to about 10.

Representative guanidino substituent groups that are shown in formula III and IV are disclosed in co-owned U.S. patent application Ser. No. 09/349,040, entitled “Functionalized Oligomers”, filed Jul. 7, 1999, hereby incorporated by reference in its entirety.

Representative acetamido substituent groups are disclosed in U.S. Pat. No. 6,147,200 which is hereby incorporated by reference in its entirety.

Representative dimethylaminoethyloxyethyl substituent groups are disclosed in International Patent Application PCT/US99/17895, entitled “2′-O-Dimethylaminoethyloxyethyl-Oligomeric compounds”, filed Aug. 6, 1999, hereby incorporated by reference in its entirety.

Modified Nucleobases/Naturally Occurring Nucleobases

Oligomeric compounds may also include nucleobase (often referred to in the art simply as “base” or “heterocyclic base moiety”) modifications or substitutions. As used herein, “unmodified” or “natural” nucleobases include the purine bases adenine (A) and guanine (G), and the pyrimidine bases thymine (T), cytosine (C) and uracil (U). Modified nucleobases also referred herein as heterocyclic base moieties include other synthetic and natural nucleobases such as 5-methylcytosine (5-me-C), 5-hydroxymethyl cytosine, xanthine, hypoxanthine, 2-aminoadenine, 6-methyl and other alkyl derivatives of adenine and guanine, 2-propyl and other alkyl derivatives of adenine and guanine, 2-thiouracil, 2-thiothymine and 2-thiocytosine, 5-halouracil and cytosine, 5-propynyl (—C≡C—CH₃) uracil and cytosine and other alkynyl derivatives of pyrimidine bases, 6-azo uracil, cytosine and thymine, 5-uracil (pseudouracil), 4-thiouracil, 8-halo, 8-amino, 8-thiol, 8-thioalkyl, 8-hydroxyl and other 8-substituted adenines and guanines, 5-halo particularly 5-bromo, 5-trifluoromethyl and other 5-substituted uracils and cytosines, 7-methylguanine and 7-methyladenine, 2-F-adenine, 2-amino-adenine, 8-azaguanine and 8-azaadenine, 7-deazaguanine and 7-deazaadenine and 3-deazaguanine and 3-deazaadenine.

Heterocyclic base moieties may also include those in which the purine or pyrimidine base is replaced with other heterocycles, for example 7-deaza-adenine, 7-deazaguanosine, 2-aminopyridine and 2-pyridone. Further nucleobases include those disclosed in U.S. Pat. No. 3,687,808, those disclosed in The Concise Encyclopedia Of Polymer Science And Engineering, pages 858-859, Kroschwitz, J. I., ed. John Wiley & Sons, 1990, those disclosed by Englisch et al., Angewandte Chemie, International Edition, 1991, 30, 613, and those disclosed by Sanghvi, Y. S., Chapter 15, Antisense Research and Applications, pages 289-302, Crooke, S. T. and Lebleu, B., ed., CRC Press, 1993. Certain of these nucleobases are particularly useful for increasing the binding affinity of the oligomeric compounds of the invention. These include 5-substituted pyrimidines, 6-azapyrimidines and N-2, N-6 and O-6 substituted purines, including 2-aminopropyladenine, 5-propynyluracil and 5-propynylcytosine. 5-methylcytosine substitutions have been shown to increase nucleic acid duplex stability by 0.6-1.2° C. (Sanghvi, Y. S., Crooke, S. T. and Lebleu, B., eds., Antisense Research and Applications, CRC Press, Boca Raton, 1993, pp. 276-278) and are presently preferred base substitutions, even more particularly when combined with 2′-O-methoxyethyl sugar modifications.

In one aspect of the present invention oligomeric compounds are prepared having polycyclic heterocyclic compounds in place of one or more heterocyclic base moieties. A number of tricyclic heterocyclic compounds have been previously reported. These compounds are routinely used in antisense applications to increase the binding properties of the modified strand to a target strand. The most studied modifications are targeted to guanosines hence they have been termed G-clamps or cytidine analogs. Many of these polycyclic heterocyclic compounds have the general formula:

Representative cytosine analogs that make 3 hydrogen bonds with a guanosine in a second strand include 1,3-diazaphenoxazine-2-one (R₁₀=O, R₁₁-R₁₄=H) [Kurchavov, et al., Nucleosides and Nucleotides, 1997, 16, 1837-1846], 1,3-diazaphenothiazine-2-one (R₁₀=S, R₁₁-R₁₄=H), [Lin, K.-Y.; Jones, R. J.; Matteucci, M. J. Am. Chem. Soc. 1995, 117, 3873-3874] and 6,7,8,9-tetrafluoro-1,3-diazaphenoxazine-2-one (R₁₀=O, R₁₁-R₁₄=F) [Wang, J.; Lin, K.-Y., Matteucci, M. Tetrahedron Lett. 1998, 39, 8385-8388]. Incorporated into oligonucleotides these base modifications were shown to hybridize with complementary guanine and the latter was also shown to hybridize with adenine and to enhance helical thermal stability by extended stacking interactions (also see U.S. patent application entitled “Modified Peptide Nucleic Acids” filed May 24, 2002, Ser. No. 10/155,920; and U.S. patent application entitled “Nuclease Resistant Chimeric Oligonucleotides” filed May 24, 2002, Ser. No. 10/013,295, both of which are commonly owned with this application and are herein incorporated by reference in their entirety).

Further helix-stabilizing properties have been observed when a cytosine analog/substitute has an aminoethoxy moiety attached to the rigid 1,3-diazaphenoxazine-2-one scaffold (R₁₀=O, R₁₁=—O—(CH₂)₂—NH₂, R₁₂₋₁₄=H) [Lin, K.-Y.; Matteucci, M. J. Am. Chem. Soc. 1998, 120, 8531-8532]. Binding studies demonstrated that a single incorporation could enhance the binding affinity of a model oligonucleotide to its complementary target DNA or RNA with a ΔT_(m) of up to 18° relative to 5-methyl cytosine (dC5^(me)), which is the highest known affinity enhancement for a single modification, yet. On the other hand, the gain in helical stability does not compromise the specificity of the oligonucleotides. The T_(m) data indicate an even greater discrimination between the perfect match and mismatched sequences compared to dC5^(me). It was suggested that the tethered amino group serves as an additional hydrogen bond donor to interact with the Hoogsteen face, namely the O6, of a complementary guanine thereby forming 4 hydrogen bonds. This means that the increased affinity of G-clamp is mediated by the combination of extended base stacking and additional specific hydrogen bonding.

Further tricyclic heterocyclic compounds and methods of using them that are amenable to the present invention are disclosed in U.S. Pat. No. 6,028,183, which issued on May 22, 2000, and U.S. Pat. No. 6,007,992, which issued on Dec. 28, 1999, the contents of both are commonly assigned with this application and are incorporated herein in their entirety.

The enhanced binding affinity of the phenoxazine derivatives together with their uncompromised sequence specificity make them valuable nucleobase analogs for the development of more potent antisense-based drugs. In fact, promising data have been derived from in vitro experiments demonstrating that heptanucleotides containing phenoxazine substitutions are capable to activate RNaseH, enhance cellular uptake and exhibit an increased antisense activity [Lin, K-Y; Matteucci, M. J. Am. Chem. Soc. 1998, 120, 8531-8532]. The activity enhancement was even more pronounced in case of G-clamp, as a single substitution was shown to significantly improve the in vitro potency of a 20mer 2′-deoxyphosphorothioate oligonucleotides [Flanagan, W. M.; Wolf, J. J.; Olson, P.; Grant, D.; Lin, K.-Y.; Wagner, R. W.; Matteucci, M. Proc. Natl. Acad. Sci. USA, 1999, 96, 3513-3518]. Nevertheless, to optimize oligonucleotide design and to better understand the impact of these heterocyclic modifications on the biological activity, it is important to evaluate their effect on the nuclease stability of the oligomers.

Further modified polycyclic heterocyclic compounds useful as heterocyclic bases are disclosed in but not limited to, the above noted U.S. Pat. No. 3,687,808, as well as U.S. Pat. Nos. 4,845,205; 5,130,302; 5,134,066; 5,175,273; 5,367,066; 5,432,272; 5,434,257; 5,457,187; 5,459,255; 5,484,908; 5,502,177; 5,525,711; 5,552,540; 5,587,469; 5,594,121, 5,596,091; 5,614,617; 5,645,985; 5,646,269; 5,750,692; 5,830,653; 5,763,588; 6,005,096; and 5,681,941, and U.S. patent application Ser. No. 09/996,292 filed Nov. 28, 2001, certain of which are commonly owned with the instant application, and each of which is herein incorporated by reference.

Conjugates

A further preferred substitution that can be appended to the oligomeric compounds of the invention involves the linkage of one or more moieties or conjugates which enhance the activity, cellular distribution or cellular uptake of the resulting oligomeric compounds. In one embodiment such modified oligomeric compounds are prepared by covalently attaching conjugate groups to functional groups such as hydroxyl or amino groups. Conjugate groups of the invention include intercalators, reporter molecules, polyamines, polyamides, polyethylene glycols, polyethers, groups that enhance the pharmacodynamic properties of oligomers, and groups that enhance the pharmacokinetic properties of oligomers. Typical conjugates groups include cholesterols, lipids, phospholipids, biotin, phenazine, folate, phenanthridine, anthraquinone, acridine, fluoresceins, rhodamines, coumarins, and dyes. Groups that enhance the pharmacodynamic properties, in the context of this invention, include groups that improve oligomer uptake, enhance oligomer resistance to degradation, and/or strengthen sequence-specific hybridization with RNA. Groups that enhance the pharmacokinetic properties, in the context of this invention, include groups that improve oligomer uptake, distribution, metabolism or excretion. Representative conjugate groups are disclosed in International Patent Application PCT/US92/09196, filed Oct. 23, 1992 the entire disclosure of which is incorporated herein by reference. Conjugate moieties include but are not limited to lipid moieties such as a cholesterol moiety (Letsinger et al., Proc. Natl. Acad. Sci. USA, 1989, 86, 6553-6556), cholic acid (Manoharan et al., Bioorg. Med. Chem. Let., 1994, 4, 1053-1060), a thioether, e.g., hexyl-S-tritylthiol (Manoharan et al., Ann. N.Y. Acad. Sci., 1992, 660, 306-309; Manoharan et al., Bioorg. Med. Chem. Let., 1993, 3, 2765-2770), a thiocholesterol (Oberhauser et al., Nucl. Acids Res., 1992, 20, 533-538), an aliphatic chain, e.g., dodecandiol or undecyl residues (Saison-Behmoaras et al., EMBO J., 1991, 10, 1111-1118; Kabanov et al., FEBS Lett., 1990, 259, 327-330; Svinarchuk et al., Biochimie, 1993, 75, 49-54), a phospholipid, e.g., di-hexadecyl-rac-glycerol or triethylammonium 1,2-di-O-hexadecyl-rac-glycero-3-H-phosphonate (Manoharan et al., Tetrahedron Lett., 1995, 36, 3651-3654; Shea et al., Nucl. Acids Res., 1990, 18, 3777-3783), a polyamine or a polyethylene glycol chain (Manoharan et al., Nucleosides & Nucleotides, 1995, 14, 969-973), or adamantane acetic acid (Manoharan et al., Tetrahedron Lett., 1995, 36, 3651-3654), a palmityl moiety (Mishra et al., Biochim. Biophys. Acta, 1995, 1264, 229-237), or an octadecylamine or hexylamino-carbonyl-oxycholesterol moiety (Crooke et al., J. Pharmacol. Exp. Ther., 1996, 277, 923-937.

The oligomeric compounds of the invention may also be conjugated to active drug substances, for example, aspirin, warfarin, phenylbutazone, ibuprofen, suprofen, fenbufen, ketoprofen, (S)-(+)-pranoprofen, carprofen, dansylsarcosine, 2,3,5-triiodobenzoic acid, flufenamic acid, folinic acid, a benzothiadiazide, chlorothiazide, a diazepine, indomethicin, a barbiturate, a cephalosporin, a sulfa drug, an antidiabetic, an antibacterial or an antibiotic. Oligonucleotide-drug conjugates and their preparation are described in U.S. patent application Ser. No. 09/334,130 (filed Jun. 15, 1999) which is incorporated herein by reference in its entirety.

Representative United States patents that teach the preparation of such oligonucleotide conjugates include, but are not limited to, U.S. Pat. Nos. 4,828,979; 4,948,882; 5,218,105; 5,525,465; 5,541,313; 5,545,730; 5,552,538; 5,578,717, 5,580,731; 5,580,731; 5,591,584; 5,109,124; 5,118,802; 5,138,045; 5,414,077; 5,486,603; 5,512,439; 5,578,718; 5,608,046; 4,587,044; 4,605,735; 4,667,025; 4,762,779; 4,789,737; 4,824,941; 4,835,263; 4,876,335; 4,904,582; 4,958,013; 5,082,830; 5,112,963; 5,214,136; 5,082,830; 5,112,963; 5,214,136; 5,245,022; 5,254,469; 5,258,506; 5,262,536; 5,272,250; 5,292,873; 5,317,098; 5,371,241, 5,391,723; 5,416,203, 5,451,463; 5,510,475; 5,512,667; 5,514,785; 5,565,552; 5,567,810; 5,574,142; 5,585,481; 5,587,371; 5,595,726; 5,597,696; 5,599,923; 5,599,928 and 5,688,941, certain of which are commonly owned with the instant application, and each of which is herein incorporated by reference.

Chimeric Oligomeric Compounds

It is not necessary for all positions in an oligomeric compound to be uniformly modified, and in fact more than one of the aforementioned modifications may be incorporated in a single oligomeric compound or even at a single monomeric subunit such as a nucleoside within a oligomeric compound. The present invention also includes oligomeric compounds which are chimeric oligomeric compounds. “Chimeric” oligomeric compounds or “chimeras,” in the context of this invention, are oligomeric compounds that contain two or more chemically distinct regions, each made up of at least one monomer unit, i.e., a nucleotide in the case of a nucleic acid based oligomer.

Chimeric oligomeric compounds typically contain at least one region modified so as to confer increased resistance to nuclease degradation, increased cellular uptake, and/or increased binding affinity for the target nucleic acid. An additional region of the oligomeric compound may serve as a substrate for enzymes capable of cleaving RNA:DNA or RNA:RNA hybrids. By way of example, RNase H is a cellular endonuclease which cleaves the RNA strand of an RNA:DNA duplex. Activation of RNase H, therefore, results in cleavage of the RNA target, thereby greatly enhancing the efficiency of inhibition of gene expression. Consequently, comparable results can often be obtained with shorter oligomeric compounds when chimeras are used, compared to for example phosphorothioate deoxyoligonucleotides hybridizing to the same target region. Cleavage of the RNA target can be routinely detected by gel electrophoresis and, if necessary, associated nucleic acid hybridization techniques known in the art.

Chimeric oligomeric compounds of the invention may be formed as composite structures of two or more oligonucleotides, oligonucleotide analogs, oligonucleosides and/or oligonucleotide mimetics as described above. Such oligomeric compounds have also been referred to in the art as hybrids hemimers, gapmers or inverted gapmers. Representative United States patents that teach the preparation of such hybrid structures include, but are not limited to, U.S. Pat. Nos. 5,013,830; 5,149,797; 5,220,007; 5,256,775; 5,366,878; 5,403,711; 5,491,133; 5,565,350; 5,623,065; 5,652,355; 5,652,356; and 5,700,922, certain of which are commonly owned with the instant application, and each of which is herein incorporated by reference in its entirety.

3′-endo Modifications

In one aspect of the present invention oligomeric compounds include nucleosides synthetically modified to induce a 3′-endo sugar conformation. A nucleoside can incorporate synthetic modifications of the heterocyclic base, the sugar moiety or both to induce a desired 3′-endo sugar conformation. These modified nucleosides are used to mimic RNA like nucleosides so that particular properties of an oligomeric compound can be enhanced while maintaining the desirable 3′-endo conformational geometry. There is an apparent preference for an RNA type duplex (A form helix, predominantly 3′-endo) as a requirement (e.g. trigger) of RNA interference which is supported in part by the fact that duplexes composed of 2′-deoxy-2′-F-nucleosides appears efficient in triggering RNAi response in the C. elegans system. Properties that are enhanced by using more stable 3′-endo nucleosides include but aren't limited to modulation of pharmacokinetic properties through modification of protein binding, protein off-rate, absorption and clearance; modulation of nuclease stability as well as chemical stability; modulation of the binding affinity and specificity of the oligomer (affinity and specificity for enzymes as well as for complementary sequences); and increasing efficacy of RNA cleavage. The present invention provides oligomeric triggers of RNAi having one or more nucleosides modified in such a way as to favor a C3′-endo type conformation.

Nucleoside conformation is influenced by various factors including substitution at the 2′, 3′ or 4′-positions of the pentofuranosyl sugar. Electronegative substituents generally prefer the axial positions, while sterically demanding substituents generally prefer the equatorial positions (Principles of Nucleic Acid Structure, Wolfgang Sanger, 1984, Springer-Verlag.) Modification of the 2′ position to favor the 3′-endo conformation can be achieved while maintaining the 2′-OH as a recognition element (Gallo et al., Tetrahedron (2001), 57, 5707-5713. Harry-O'kuru et al., J. Org. Chem., (1997), 62(6), 1754-1759 and Tang et al., J. Org. Chem. (1999), 64, 747-754.) Alternatively, preference for the 3′-endo conformation can be achieved by deletion of the 2′-OH as exemplified by 2′deoxy-2′F-nucleosides (Kawasaki et al., J. Med. Chem. (1993), 36, 831-841), which adopts the 3′-endo conformation positioning the electronegative fluorine atom in the axial position. Other modifications of the ribose ring, for example substitution at the 4′-position to give 4′-F modified nucleosides (Guillerm et al., Bioorganic and Medicinal Chemistry Letters (1995), 5, 1455-1460 and Owen et al., J. Org. Chem. (1976), 41, 3010-3017), or for example modification to yield methanocarba nucleoside analogs (Jacobson et al., J. Med. Chem. Lett. (2000), 43, 2196-2203 and Lee et al., Bioorganic and Medicinal Chemistry Letters (2001), 11, 1333-1337) also induce preference for the 3′-endo conformation. Along similar lines, oligomeric triggers of RNAi response might be composed of one or more nucleosides modified in such a way that conformation is locked into a C3′-endo type conformation, i.e. Locked Nucleic Acid (LNA, Singh et al, Chem. Commun. (1998), 4, 455-456), and ethylene bridged Nucleic Acids (ENA, Morita et al, Bioorganic & Medicinal Chemistry Letters (2002), 12, 73-76.) Examples of modified nucleosides amenable to the present invention are shown below in Table I. These examples are meant to be representative and not exhaustive.

TABLE I

The preferred conformation of modified nucleosides and their oligomers can be estimated by various methods such as molecular dynamics calculations, nuclear magnetic resonance spectroscopy and CD measurements. Hence, modifications predicted to induce RNA like conformations, A-form duplex geometry in an oligomeric context, are selected for use in the modified oligonucleotides of the present invention. The synthesis of numerous of the modified nucleosides amenable to the present invention are known in the art (see for example, Chemistry of Nucleosides and Nucleotides Vol 1-3, ed. Leroy B. Townsend, 1988, Plenum press., and the examples section below.) Nucleosides known to be inhibitors/substrates for RNA dependent RNA polymerases (for example HCV NS5B

In one aspect, the present invention is directed to oligonucleotides that are prepared having enhanced properties compared to native RNA against nucleic acid targets. A target is identified and an oligonucleotide is selected having an effective length and sequence that is complementary to a portion of the target sequence. Each nucleoside of the selected sequence is scrutinized for possible enhancing modifications. A preferred modification would be the replacement of one or more RNA nucleosides with nucleosides that have the same 3′-endo conformational geometry. Such modifications can enhance chemical and nuclease stability relative to native RNA while at the same time being much cheaper and easier to synthesize and/or incorporate into an oligonucleotide. The selected sequence can be further divided into regions and the nucleosides of each region evaluated for enhancing modifications that can be the result of a chimeric configuration. Consideration is also given to the 5′ and 3′-termini as there are often advantageous modifications that can be made to one or more of the terminal nucleosides. The oligomeric compounds of the present invention include at least one 5′-modified phosphate group on a single strand or on at least one 5′-position of a double stranded sequence or sequences. Further modifications are also considered such as internucleoside linkages, conjugate groups, substitute sugars or bases, substitution of one or more nucleosides with nucleoside mimetics and any other modification that can enhance the selected sequence for its intended target.

The terms used to describe the conformational geometry of homoduplex nucleic acids are “A Form” for RNA and “B Form” for DNA. The respective conformational geometry for RNA and DNA duplexes was determined from X-ray diffraction analysis of nucleic acid fibers (Arnott and Hukins, Biochem. Biophys. Res. Comm., 1970, 47, 1504.) In general, RNA:RNA duplexes are more stable and have higher melting temperatures (Tm's) than DNA:DNA duplexes (Sanger et al., Principles of Nucleic Acid Structure, 1984, Springer-Verlag; New York, N.Y.; Lesnik et al., Biochemistry, 1995, 34, 10807-10815; Conte et al., Nucleic Acids Res., 1997, 25, 2627-2634). The increased stability of RNA has been attributed to several structural features, most notably the improved base stacking interactions that result from an A-form geometry (Searle et al., Nucleic Acids Res., 1993, 21, 2051-2056). The presence of the 2′ hydroxyl in RNA biases the sugar toward a C3′ endo pucker, i.e., also designated as Northern pucker, which causes the duplex to favor the A-form geometry. In addition, the 2′ hydroxyl groups of RNA can form a network of water mediated hydrogen bonds that help stabilize the RNA duplex (Egli et al., Biochemistry, 1996, 35, 8489-8494). On the other hand, deoxy nucleic acids prefer a C2′ endo sugar pucker, i.e., also known as Southern pucker, which is thought to impart a less stable B-form geometry (Sanger, W. (1984) Principles of Nucleic Acid Structure, Springer-Verlag, New York, N.Y.). As used herein, B-form geometry is inclusive of both C2′-endo pucker and O4′-endo pucker. This is consistent with Berger, et. al., Nucleic Acids Research, 1998, 26, 2473-2480, who pointed out that in considering the furanose conformations which give rise to B-form duplexes consideration should also be given to a O4′-endo pucker contribution.

DNA:RNA hybrid duplexes, however, are usually less stable than pure RNA:RNA duplexes, and depending on their sequence may be either more or less stable than DNA:DNA duplexes (Searle et al., Nucleic Acids Res., 1993, 21, 2051-2056). The structure of a hybrid duplex is intermediate between A- and B-form geometries, which may result in poor stacking interactions (Lane et al., Eur. J. Biochem., 1993, 215, 297-306; Fedoroff et al., J. Mol. Biol., 1993, 233, 509-523; Gonzalez et al., Biochemistry, 1995, 34, 4969-4982; Horton et al., J. Mol. Biol., 1996, 264, 521-533). The stability of the duplex formed between a target RNA and a synthetic sequence is central to therapies such as but not limited to antisense and RNA interference as these mechanisms require the binding of a synthetic oligonucleotide strand to an RNA target strand. In the case of antisense, effective inhibition of the mRNA requires that the antisense DNA have a very high binding affinity with the mRNA. Otherwise the desired interaction between the synthetic oligonucleotide strand and target mRNA strand will occur infrequently, resulting in decreased efficacyl

One routinely used method of modifying the sugar puckering is the substitution of the sugar at the 2′-position with a substituent group that influences the sugar geometry. The influence on ring conformation is dependant on the nature of the substituent at the 2′-position. A number of different substituents have been studied to determine their sugar puckering effect. For example, 2′-halogens have been studied showing that the 2′-fluoro derivative exhibits the largest population (65%) of the C3′-endo form, and the 2′-iodo exhibits the lowest population (7%). The populations of adenosine (2′-OH) versus deoxyadenosine (2′-H) are 36% and 19%, respectively. Furthermore, the effect of the 2′-fluoro group of adenosine dimers (2′-deoxy-2′-fluoroadenosine-2′-deoxy-2′-fluoro-adenosine) is further correlated to the stabilization of the stacked conformation.

As expected, the relative duplex stability can be enhanced by replacement of 2′-OH groups with 2′-F groups thereby increasing the C3′-endo population. It is assumed that the highly polar nature of the 2′-F bond and the extreme preference for C3′-endo puckering may stabilize the stacked conformation in an A-form duplex. Data from UV hypochromicity, circular dichroism, and ¹H NMR also indicate that the degree of stacking decreases as the electronegativity of the halo substituent decreases. Furthermore, steric bulk at the 2′-position of the sugar moiety is better accommodated in an A-form duplex than a B-form duplex. Thus, a 2′-substituent on the 3′-terminus of a dinucleoside monophosphate is thought to exert a number of effects on the stacking conformation: steric repulsion, furanose puckering preference, electrostatic repulsion, hydrophobic attraction, and hydrogen bonding capabilities. These substituent effects are thought to be determined by the molecular size, electronegativity, and hydrophobicity of the substituent. Melting temperatures of complementary strands is also increased with the 2′-substituted adenosine diphosphates. It is not clear whether the 3′-endo preference of the conformation or the presence of the substituent is responsible for the increased binding. However, greater overlap of adjacent bases (stacking) can be achieved with the 3′-endo conformation.

One synthetic 2′-modification that imparts increased nuclease resistance and a very high binding affinity to nucleotides is the 2-methoxyethoxy (2′-MOE, 2′-OCH₂CH₂OCH₃) side chain (Baker et al., J. Biol. Chem., 1997, 272, 11944-12000). One of the immediate advantages of the 2′-MOE substitution is the improvement in binding affinity, which is greater than many similar 2′ modifications such as O-methyl, O-propyl, and O-aminopropyl. Oligonucleotides having the 2′-O-methoxyethyl substituent also have been shown to be antisense inhibitors of gene expression with promising features for in vivo use (Martin, P., Helv. Chim. Acta, 1995, 78, 486-504; Altmann et al., Chimia, 1996, 50, 168-176; Altmann et al., Biochem. Soc. Trans., 1996, 24, 630-637; and Altmann et al., Nucleosides Nucleotides, 1997, 16, 917-926). Relative to DNA, the oligonucleotides having the 2′-MOE modification displayed improved RNA affinity and higher nuclease resistance. Chimeric oligonucleotides having 2′-MOE substituents in the wing nucleosides and an internal region of deoxy-phosphorothioate nucleotides (also termed a gapped oligonucleotide or gapmer) have shown effective reduction in the growth of tumors in animal models at low doses. 2′-MOE substituted oligonucleotides have also shown outstanding promise as antisense agents in several disease states. One such MOE substituted oligonucleotide is presently being investigated in clinical trials for the treatment of CMV retinitis.

Chemistries Defined

Unless otherwise defined herein, alkyl means C₁-C₁₂, preferably C₁-C₈, and more preferably C₁-C₆, straight or (where possible) branched chain aliphatic hydrocarbyl.

Unless otherwise defined herein, heteroalkyl means C₁-C₁₂, preferably C₁-C₈, and more preferably C₁-C₆, straight or (where possible) branched chain aliphatic hydrocarbyl containing at least one, and preferably about 1 to about 3, hetero atoms in the chain, including the terminal portion of the chain. Preferred heteroatoms include N, O and S.

Unless otherwise defined herein, cycloalkyl means C₃-C₁₂, preferably C₃-C₈, and more preferably C₃-C₆, aliphatic hydrocarbyl ring.

Unless otherwise defined herein, alkenyl means C₂-C₁₂, preferably C₂-C₈, and more preferably C₂-C₆ alkenyl, which may be straight or (where possible) branched hydrocarbyl moiety, which contains at least one carbon-carbon double bond.

Unless otherwise defined herein, alkynyl means C₂-C₁₂, preferably C₂-C₈, and more preferably C₂-C₆ alkynyl, which may be straight or (where possible) branched hydrocarbyl moiety, which contains at least one carbon-carbon triple bond.

Unless otherwise defined herein, heterocycloalkyl means a ring moiety containing at least three ring members, at least one of which is carbon, and of which 1, 2 or three ring members are other than carbon. Preferably the number of carbon atoms varies from 1 to about 12, preferably 1 to about 6, and the total number of ring members varies from three to about 15, preferably from about 3 to about 8. Preferred ring heteroatoms are N, O and S. Preferred heterocycloalkyl groups include morpholino, thiomorpholino, piperidinyl, piperazinyl, homopiperidinyl, homopiperazinyl, homomorpholino, homothiomorpholino, pyrrolodinyl, tetrahydrooxazolyl, tetrahydroimidazolyl, tetrahydrothiazolyl, tetrahydroisoxazolyl, tetrahydropyrrazolyl, furanyl, pyranyl, and tetrahydroisothiazolyl.

Unless otherwise defined herein, aryl means any hydrocarbon ring structure containing at least one aryl ring. Preferred aryl rings have about 6 to about 20 ring carbons. Especially preferred aryl rings include phenyl, napthyl, anthracenyl, and phenanthrenyl.

Unless otherwise defined herein, hetaryl means a ring moiety containing at least one fully unsaturated ring, the ring consisting of carbon and non-carbon atoms. Preferably the ring system contains about 1 to about 4 rings. Preferably the number of carbon atoms varies from 1 to about 12, preferably 1 to about 6, and the total number of ring members varies from three to about 15, preferably from about 3 to about 8. Preferred ring heteroatoms are N, O and S. Preferred hetaryl moieties include pyrazolyl, thiophenyl, pyridyl, imidazolyl, tetrazolyl, pyridyl, pyrimidinyl, purinyl, quinazolinyl, quinoxalinyl, benzimidazolyl, benzothiophenyl, etc.

Unless otherwise defined herein, where a moiety is defined as a compound moiety, such as hetarylalkyl (hetaryl and alkyl), aralkyl (aryl and alkyl), etc., each of the sub-moieties is as defined herein.

Unless otherwise defined herein, an electron withdrawing group is a group, such as the cyano or isocyanato group that draws electronic charge away from the carbon to which it is attached. Other electron withdrawing groups of note include those whose electronegativities exceed that of carbon, for example halogen, nitro, or phenyl substituted in the ortho- or para-position with one or more cyano, isothiocyanato, nitro or halo groups.

Unless otherwise defined herein, the terms halogen and halo have their ordinary meanings. Preferred halo (halogen) substituents are Cl, Br, and I. The aforementioned optional substituents are, unless otherwise herein defined, suitable substituents depending upon desired properties. Included are halogens (Cl, Br, I), alkyl, alkenyl, and alkynyl moieties, NO₂, NH₃ (substituted and unsubstituted), acid moieties (e.g. —CO₂H, —OSO₃H₂, etc.), heterocycloalkyl moieties, hetaryl moieties, aryl moieties, etc. In all the preceding formulae, the squiggle (˜) indicates a bond to an oxygen or sulfur of the 5′-phosphate.

Phosphate protecting groups include those described in U.S. Pat. Nos. 5,760,209, 5,614,621, 6,051,699, 6,020,475, 6,326,478, 6,169,177, 6,121,437, 6,465,628 each of which is expressly incorporated herein by reference in its entirety.

Screening, Target Validation and Drug Discovery

For use in screening and target validation, the compounds and compositions of the invention are used to modulate the expression of a selected protein. “Modulators” are those oligomeric compounds and compositions that decrease or increase the expression of a nucleic acid molecule encoding a protein and which comprise at least an 8-nucleobase portion which is complementary to a preferred target segment. The screening method comprises the steps of contacting a preferred target segment of a nucleic acid molecule encoding a protein with one or more candidate modulators, and selecting for one or more candidate modulators which decrease or increase the expression of a nucleic acid molecule encoding a protein. Once it is shown that the candidate modulator or modulators are capable of modulating (e.g. either decreasing or increasing) the expression of a nucleic acid molecule encoding a peptide, the modulator may then be employed in further investigative studies of the function of the peptide, or for use as a research, diagnostic, or therapeutic agent in accordance with the present invention.

The conduction such screening and target validation studies, oligomeric compounds of invention can be used combined with their respective complementary strand oligomeric compound to form stabilized double-stranded (duplexed) oligonucleotides. Double stranded oligonucleotide moieties have been shown to modulate target expression and regulate translation as well as RNA processing via an antisense mechanism. Moreover, the double-stranded moieties may be subject to chemical modifications (Fire et al., Nature, 1998, 391, 806-811; Timmons and Fire, Nature 1998, 395, 854; Timmons et al., Gene, 2001, 263, 103-112; Tabara et al., Science, 1998, 282, 430-431; Montgomery et al., Proc. Natl. Acad. Sci. USA, 1998, 95, 15502-15507; Tuschl et al., Genes Dev., 1999, 13, 3191-3197; Elbashir et al., Nature, 2001, 411, 494-498; Elbashir et al., Genes Dev. 2001, 15, 188-200; Nishikura et al., Cell (2001), 107, 415-416; and Bass et al., Cell (2000), 101, 235-238.) For example, such double-stranded moieties have been shown to inhibit the target by the classical hybridization of antisense strand of the duplex to the target, thereby triggering enzymatic degradation of the target (Tijsterman et al., Science, 2002, 295, 694-697).

For use in drug discovery and target validation, oligomeric compounds of the present invention are used to elucidate relationships that exist between proteins and a disease state, phenotype, or condition. These methods include detecting or modulating a target peptide comprising contacting a sample, tissue, cell, or organism with the oligomeric compounds and compositions of the present invention, measuring the nucleic acid or protein level of the target and/or a related phenotypic or chemical endpoint at some time after treatment, and optionally comparing the measured value to a non-treated sample or sample treated with a further oligomeric compound of the invention. These methods can also be performed in parallel or in combination with other experiments to determine the function of unknown genes for the process of target validation or to determine the validity of a particular gene product as a target for treatment or prevention of a disease or disorder.

Kits, Research Reagents, Diagnostics, and Therapeutics

The oligomeric compounds and compositions of the present invention can additionally be utilized for diagnostics, therapeutics, prophylaxis and as research reagents and kits. Such uses allows for those of ordinary skill to elucidate the function of particular genes or to distinguish between functions of various members of a biological pathway.

For use in kits and diagnostics, the oligomeric compounds and compositions of the present invention, either alone or in combination with other compounds or therapeutics, can be used as tools in differential and/or combinatorial analyses to elucidate expression patterns of a portion or the entire complement of genes expressed within cells and tissues.

As one non-limiting example, expression patterns within cells or tissues treated with one or more compounds or compositions of the invention are compared to control cells or tissues not treated with the compounds or compositions and the patterns produced are analyzed for differential levels of gene expression as they pertain, for example, to disease association, signaling pathway, cellular localization, expression level, size, structure or function of the genes examined. These analyses can be performed on stimulated or unstimulated cells and in the presence or absence of other compounds that affect expression patterns.

Examples of methods of gene expression analysis known in the art include DNA arrays or microarrays (Brazma and Vilo, FEBS Lett., 2000, 480, 17-24; Celis, et al., FEBS Lett., 2000, 480, 2-16), SAGE (serial analysis of gene expression) (Madden, et al., Drug Discov. Today, 2000, 5, 415-425), READS (restriction enzyme amplification of digested cDNAs) (Prashar and Weissman, Methods Enzymol., 1999, 303, 258-72), TOGA (total gene expression analysis) (Sutcliffe, et al., Proc. Natl. Acad. Sci. U.S.A, 2000, 97, 1976-81), protein arrays and proteomics (Celis, et al., FEBS Lett., 2000, 480, 2-16; Jungblut, et al., Electrophoresis, 1999, 20, 2100-10), expressed sequence tag (EST) sequencing (Celis, et al., FEBS Lett., 2000, 480, 2-16; Larsson, et al., J. Biotechnol., 2000, 80, 143-57), subtractive RNA fingerprinting (SuRF) (Fuchs, et al., Anal. Biochem., 2000, 286, 91-98; Larson, et al., Cytometry, 2000, 41, 203-208), subtractive cloning, differential display (DD) (Jurecic and Belmont, Curr. Opin. Microbiol., 2000, 3, 316-21), comparative genomic hybridization (Carulli, et al., J. Cell Biochem. Suppl., 1998, 31, 286-96), FISH (fluorescent in situ hybridization) techniques (Going and Gusterson, Eur. J. Cancer, 1999, 35, 1895-904) and mass spectrometry methods (To, Comb. Chem. High Throughput Screen, 2000, 3, 235-41).

The compounds and compositions of the invention are useful for research and diagnostics, because these compounds and compositions hybridize to nucleic acids encoding proteins. Hybridization of the compounds and compositions of the invention with a nucleic acid can be detected by means known in the art. Such means may include conjugation of an enzyme to the compound or composition, radiolabelling or any other suitable detection means. Kits using such detection means for detecting the level of selected proteins in a sample may also be prepared.

The specificity and sensitivity of compounds and compositions can also be harnessed by those of skill in the art for therapeutic uses. Antisense oligomeric compounds have been employed as therapeutic moieties in the treatment of disease states in animals, including humans. Antisense oligonucleotide drugs, including ribozymes, have been safely and effectively administered to humans and numerous clinical trials are presently underway. It is thus established that oligomeric compounds can be useful therapeutic modalities that can be configured to be useful in treatment regimes for the treatment of cells, tissues and animals, especially humans.

For therapeutics, an animal, preferably a human, suspected of having a disease or disorder that can be treated by modulating the expression of a selected protein is treated by administering the compounds and compositions. For example, in one non-limiting embodiment, the methods comprise the step of administering to the animal in need of treatment, a therapeutically effective amount of a protein inhibitor. The protein inhibitors of the present invention effectively inhibit the activity of the protein or inhibit the expression of the protein. In one embodiment, the activity or expression of a protein in an animal is inhibited by about 10%. Preferably, the activity or expression of a protein in an animal is inhibited by about 30%. More preferably, the activity or expression of a protein in an animal is inhibited by 50% or more.

For example, the reduction of the expression of a protein may be measured in serum, adipose tissue, liver or any other body fluid, tissue or organ of the animal. Preferably, the cells contained within the fluids, tissues or organs being analyzed contain a nucleic acid molecule encoding a protein and/or the protein itself.

The compounds and compositions of the invention can be utilized in pharmaceutical compositions by adding an effective amount of the compound or composition to a suitable pharmaceutically acceptable diluent or carrier. Use of the oligomeric compounds and methods of the invention may also be useful prophylactically.

Formulations

The compounds and compositions of the invention may also be admixed, encapsulated, conjugated or otherwise associated with other molecules, molecule structures or mixtures of compounds, as for example, liposomes, receptor-targeted molecules, oral, rectal, topical or other formulations, for assisting in uptake, distribution and/or absorption. Representative United States patents that teach the preparation of such uptake, distribution and/or absorption-assisting formulations include, but are not limited to, U.S. Pat. Nos. 5,108,921; 5,354,844; 5,416,016; 5,459,127; 5,521,291; 5,543,158; 5,547,932; 5,583,020; 5,591,721; 4,426,330; 4,534,899; 5,013,556; 5,108,921; 5,213,804; 5,227,170; 5,264,221; 5,356,633; 5,395,619; 5,416,016; 5,417,978; 5,462,854; 5,469,854; 5,512,295; 5,527,528; 5,534,259; 5,543,152; 5,556,948; 5,580,575; and 5,595,756, each of which is herein incorporated by reference.

The compounds and compositions of the invention encompass any pharmaceutically acceptable salts, esters, or salts of such esters, or any other compound which, upon administration to an animal, including a human, is capable of providing (directly or indirectly) the biologically active metabolite or residue thereof. Accordingly, for example, the disclosure is also drawn to prodrugs and pharmaceutically acceptable salts of the oligomeric compounds of the invention, pharmaceutically acceptable salts of such prodrugs, and other bioequivalents.

The term “prodrug” indicates a therapeutic agent that is prepared in an inactive form that is converted to an active form (i.e., drug) within the body or cells thereof by the action of endogenous enzymes or other chemicals and/or conditions. In particular, prodrug versions of the oligonucleotides of the invention are prepared as SATE [(S-acetyl-2-thioethyl)phosphate] derivatives according to the methods disclosed in WO 93/24510 to Gosselin et al., published Dec. 9, 1993 or in WO 94/26764 and U.S. Pat. No. 5,770,713 to Imbach et al.

The term “pharmaceutically acceptable salts” refers to physiologically and pharmaceutically acceptable salts of the compounds and compositions of the invention: i.e., salts that retain the desired biological activity of the parent compound and do not impart undesired toxicological effects thereto. For oligonucleotides, preferred examples of pharmaceutically acceptable salts and their uses are further described in U.S. Pat. No. 6,287,860, which is incorporated herein in its entirety.

The present invention also includes pharmaceutical compositions and formulations that include the compounds and compositions of the invention. The pharmaceutical compositions of the present invention may be administered in a number of ways depending upon whether local or systemic treatment is desired and upon the area to be treated. Administration may be topical (including ophthalmic and to mucous membranes including vaginal and rectal delivery), pulmonary, e.g., by inhalation or insufflation of powders or aerosols, including by nebulizer; intratracheal, intranasal, epidermal and transdermal), oral or parenteral. Parenteral administration includes intravenous, intraarterial, subcutaneous, intraperitoneal or intramuscular injection or infusion; or intracranial, e.g., intrathecal or intraventricular, administration. Pharmaceutical compositions and formulations for topical administration may include transdermal patches, ointments, lotions, creams, gels, drops, suppositories, sprays, liquids and powders. Conventional pharmaceutical carriers, aqueous, powder or oily bases, thickeners and the like may be necessary or desirable. Coated condoms, gloves and the like may also be useful.

The pharmaceutical formulations of the present invention, which may conveniently be presented in unit dosage form, may be prepared according to conventional techniques well known in the pharmaceutical industry. Such techniques include the step of bringing into association the active ingredients with the pharmaceutical carrier(s) or excipient(s). In general, the formulations are prepared by uniformly and intimately bringing into association the active ingredients with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product.

The compounds and compositions of the present invention may be formulated into any of many possible dosage forms such as, but not limited to, tablets, capsules, gel capsules, liquid syrups, soft gels, suppositories, and enemas. The compositions of the present invention may also be formulated as suspensions in aqueous, non-aqueous or mixed media. Aqueous suspensions may further contain substances which increase the viscosity of the suspension including, for example, sodium carboxymethylcellulose, sorbitol and/or dextran. The suspension may also contain stabilizers.

Pharmaceutical compositions of the present invention include, but are not limited to, solutions, emulsions, foams and liposome-containing formulations. The pharmaceutical compositions and formulations of the present invention may comprise one or more penetration enhancers, carriers, excipients or other active or inactive ingredients.

Emulsions are typically heterogenous systems of one liquid dispersed in another in the form of droplets usually exceeding 0.1 μm in diameter. Emulsions may contain additional components in addition to the dispersed phases, and the active drug that may be present as a solution in either the aqueous phase, oily phase or itself as a separate phase. Microemulsions are included as an embodiment of the present invention. Emulsions and their uses are well known in the art and are further described in U.S. Pat. No. 6,287,860, which is incorporated herein in its entirety.

Formulations of the present invention include liposomal formulations. As used in the present invention, the term “liposome” means a vesicle composed of amphiphilic lipids arranged in a spherical bilayer or bilayers. Liposomes are unilamellar or multilamellar vesicles which have a membrane formed from a lipophilic material and an aqueous interior that contains the composition to be delivered. Cationic liposomes are positively charged liposomes which are believed to interact with negatively charged DNA molecules to form a stable complex. Liposomes that are pH-sensitive or negatively-charged are believed to entrap DNA rather than complex with it. Both cationic and noncationic liposomes have been used to deliver DNA to cells.

Liposomes also include “sterically stabilized” liposomes, a term which, as used herein, refers to liposomes comprising one or more specialized lipids that, when incorporated into liposomes, result in enhanced circulation lifetimes relative to liposomes lacking such specialized lipids. Examples of sterically stabilized liposomes are those in which part of the vesicle-forming lipid portion of the liposome comprises one or more glycolipids or is derivatized with one or more hydrophilic polymers, such as a polyethylene glycol (PEG) moiety. Liposomes and their uses are further described in U.S. Pat. No. 6,287,860, which is incorporated herein in its entirety.

The pharmaceutical formulations and compositions of the present invention may also include surfactants. The use of surfactants in drug products, formulations and in emulsions is well known in the art. Surfactants and their uses are further described in U.S. Pat. No. 6,287,860, which is incorporated herein in its entirety.

In one embodiment, the present invention employs various penetration enhancers to effect the efficient delivery of nucleic acids, particularly oligonucleotides. In addition to aiding the diffusion of non-lipophilic drugs across cell membranes, penetration enhancers also enhance the permeability of lipophilic drugs. Penetration enhancers may be classified as belonging to one of five broad categories, i.e., surfactants, fatty acids, bile salts, chelating agents, and non-chelating non-surfactants. Penetration enhancers and their uses are further described in U.S. Pat. No. 6,287,860, which is incorporated herein in its entirety.

One of skill in the art will recognize that formulations are routinely designed according to their intended use, i.e. route of administration.

Preferred formulations for topical administration include those in which the oligonucleotides of the invention are in admixture with a topical delivery agent such as lipids, liposomes, fatty acids, fatty acid esters, steroids, chelating agents and surfactants. Preferred lipids and liposomes include neutral (e.g. dioleoylphosphatidyl DOPE ethanolamine, dimyristoylphosphatidyl choline DMPC, distearolyphosphatidyl choline) negative (e.g. dimyristoylphosphatidyl glycerol DMPG) and cationic (e.g. dioleoyltetramethylaminopropyl DOTAP and dioleoylphosphatidyl ethanolamine DOTMA).

For topical or other administration, compounds and compositions of the invention may be encapsulated within liposomes or may form complexes thereto, in particular to cationic liposomes. Alternatively, they may be complexed to lipids, in particular to cationic lipids. Preferred fatty acids and esters, pharmaceutically acceptable salts thereof, and their uses are further described in U.S. Pat. No. 6,287,860, which is incorporated herein in its entirety. Topical formulations are described in detail in U.S. patent application Ser. No. 09/315,298 filed on May 20, 1999, which is incorporated herein by reference in its entirety.

Compositions and formulations for oral administration include powders or granules, microparticulates, nanoparticulates, suspensions or solutions in water or non-aqueous media, capsules, gel capsules, sachets, tablets or minitablets. Thickeners, flavoring agents, diluents, emulsifiers, dispersing aids or binders may be desirable. Preferred oral formulations are those in which oligonucleotides of the invention are administered in conjunction with one or more penetration enhancers surfactants and chelators. Preferred surfactants include fatty acids and/or esters or salts thereof, bile acids and/or salts thereof. Preferred bile acids/salts and fatty acids and their uses are further described in U.S. Pat. No. 6,287,860, which is incorporated herein in its entirety. Also preferred are combinations of penetration enhancers, for example, fatty acids/salts in combination with bile acids/salts. A particularly preferred combination is the sodium salt of lauric acid, capric acid and UDCA. Further penetration enhancers include polyoxyethylene-9-lauryl ether, polyoxyethylene-20-cetyl ether. Compounds and compositions of the invention may be delivered orally, in granular form including sprayed dried particles, or complexed to form micro or nanoparticles. Complexing agents and their uses are further described in U.S. Pat. No. 6,287,860, which is incorporated herein in its entirety. Certain oral formulations for oligonucleotides and their preparation are described in detail in U.S. application Ser. No. 09/108,673 (filed Jul. 1, 1998), Ser. No. 09/315,298 (filed May 20, 1999) and Ser. No. 10/071,822, filed Feb. 8, 2002, each of which is incorporated herein by reference in their entirety.

Compositions and formulations for parenteral, intrathecal or intraventricular administration may include sterile aqueous solutions that may also contain buffers, diluents and other suitable additives such as, but not limited to, penetration enhancers, carrier compounds and other pharmaceutically acceptable carriers or excipients.

Certain embodiments of the invention provide pharmaceutical compositions containing one or more of the compounds and compositions of the invention and one or more other chemotherapeutic agents that function by a non-antisense mechanism. Examples of such chemotherapeutic agents include but are not limited to cancer chemotherapeutic drugs such as daunorubicin, daunomycin, dactinomycin, doxorubicin, epirubicin, idarubicin, esorubicin, bleomycin, mafosfamide, ifosfamide, cytosine arabinoside, bis-chloroethylnitrosurea, busulfan, mitomycin C, actinomycin D, mithramycin, prednisone, hydroxyprogesterone, testosterone, tamoxifen, dacarbazine, procarbazine, hexamethylmelamine, pentamethylmelamine, mitoxantrone, amsacrine, chlorambucil, methylcyclohexylnitrosurea, nitrogen mustards, melphalan, cyclophosphamide, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-azacytidine, hydroxyurea, deoxycoformycin, 4-hydroxyperoxycyclophosphoramide, 5-fluorouracil (5-FU), 5-fluorodeoxyuridine (5-FUdR), methotrexate (MTX), colchicine, taxol, vincristine, vinblastine, etoposide (VP-16), trimetrexate, irinotecan, topotecan, gemcitabine, teniposide, cisplatin and diethylstilbestrol (DES). When used with the oligomeric compounds of the invention, such chemotherapeutic agents may be used individually (e.g., 5-FU and oligonucleotide), sequentially (e.g., 5-FU and oligonucleotide for a period of time followed by MTX and oligonucleotide), or in combination with one or more other such chemotherapeutic agents (e.g., 5-FU, MTX and oligonucleotide, or 5-FU, radiotherapy and oligonucleotide). Anti-inflammatory drugs, including but not limited to nonsteroidal anti-inflammatory drugs and corticosteroids, and antiviral drugs, including but not limited to ribivirin, vidarabine, acyclovir and ganciclovir, may also be combined in compositions of the invention. Combinations of compounds and compositions of the invention and other drugs are also within the scope of this invention. Two or more combined compounds such as two oligomeric compounds or one oligomeric compound combined with further compounds may be used together or sequentially.

In another related embodiment, compositions of the invention may contain one or more of the compounds and compositions of the invention targeted to a first nucleic acid and one or more additional compounds such as antisense oligomeric compounds targeted to a second nucleic acid target. Numerous examples of antisense oligomeric compounds are known in the art. Alternatively, compositions of the invention may contain two or more oligomeric compounds and compositions targeted to different regions of the same nucleic acid target. Two or more combined compounds may be used together or sequentially

Dosing

The formulation of therapeutic compounds and compositions of the invention and their subsequent administration (dosing) is believed to be within the skill of those in the art. Dosing is dependent on severity and responsiveness of the disease state to be treated, with the course of treatment lasting from several days to several months, or until a cure is effected or a diminution of the disease state is achieved. Optimal dosing schedules can be calculated from measurements of drug accumulation in the body of the patient. Persons of ordinary skill can easily determine optimum dosages, dosing methodologies and repetition rates. Optimum dosages may vary depending on the relative potency of individual oligonucleotides, and can generally be estimated based on EC₅₀s found to be effective in in vitro and in vivo animal models. In general, dosage is from 0.01 ug to 100 g per kg of body weight, and may be given once or more daily, weekly, monthly or yearly, or even once every 2 to 20 years. Persons of ordinary skill in the art can easily estimate repetition rates for dosing based on measured residence times and concentrations of the drug in bodily fluids or tissues. Following successful treatment, it may be desirable to have the patient undergo maintenance therapy to prevent the recurrence of the disease state, wherein the oligonucleotide is administered in maintenance doses, ranging from 0.01 ug to 100 g per kg of body weight, once or more daily, to once every 20 years.

While the present invention has been described with specificity in accordance with certain of its preferred embodiments, the following examples serve only to illustrate the invention and are not intended to limit the same.

The entire disclosure of each patent, patent application, and publication cited or described in this document is hereby incorporated by reference.

EXAMPLE 1 Synthesis of Phorphorothioate Oligonucleotides

Oligonucleotides containing phosphorothioate linkages are synthesized as described in U.S. Pat. Nos. 5,264,423, 5,276,019, 5,286,717, 6,277,967 and 6,326,358.

EXAMPLE 2 Synthesis of Phosphorodithioate Oligonucltotides

Phosphorodithioate oligonucleotides are synthesized as described in U.S. Pat. Nos. 5,278,302, 5,453,496, and 5,750,666.

EXAMPLE 3 Synthesis of Phosphonate Oligonucleotides

Phosphonate-containing oligonucleotides are synthesized as described in U.S. Pat. Nos. 5,204,455, 5,789,576, 5,986,083, 6,028,188, and 5,936,080.

EXAMPLE 4 Synthesis of Phosphotriester Oligonucleotides

Phosphotriester oligonucleotides are synthesized as described in U.S. Pat. No. 5,023,243.

EXAMPLE 5 Synthesis of Alkylphosphotriester Oligonucleotides

Alkylphosphotriester oligonucleotides are synthesized as described in U.S. Pat. No. 6,015,886.

EXAMPLE 6 Synthesis of Aminoalklyphosphotriester Oligonucleotides

Oligonucleotides containing aminoalklyphosphotriester internucleoside linkages are synthesized as described in U.S. Pat. Nos. 5,536,821, 5,541,306, and 5,563,253.

EXAMPLE 7 Synthesis of 3′-5′ Phosphoroamidate Oligonucleotides

3′-5′ phosphoroamidate oligonucleotides are synthesized as described in U.S. Pat. Nos. 5,476,925, 5,726,297, 5,837,835, and 5,965,720.

EXAMPLE 8 Synthesis of Aminoalkylphosphoramidate Oligonucleotides

Oligonucleotides containing aminoalkylphosphoramidate internucleoside linkages are synthesized as described in U.S. Pat. Nos. 5,204,455, 5,519,126 and 5,536,821.

EXAMPLE 9 Synthesis of Aminoalkylphosphorothioamidate Oligonucleotides

Oligonucleotides containing aminoalklyphosphorothioamidate internucleoside linkages are synthesized as described in U.S. Pat. No. 5,536,821.

EXAMPLE 10 Synthesis of Oligonucleotides Containing Phosphinate Internucleoside Linkages

Oligonucleotides containing phosphinate internucleoside linkages are synthesized as described in U.S. Pat. No. 5,466,677.

EXAMPLE 11 Synthesis of Oligonucleotides Containing Boronated Internucleoside Phospodiester Linkages

Oligonucleotides containing boronated internucleotide phosphodiester linkages are synthesized as described in U.S. Pat. No. 5,455,233.

EXAMPLE 12 Synthesis of Oligonucleotides Formed from α-D-arabinofuranosyl Nucleoside Monomers

Oligonucleotides formed from α-D-arabinofuranosyl nucleoside monomers are synthesized as described in U.S. Pat. No. 5,177,196.

EXAMPLE 13 Synthesis of 2′-5′ Oligoadenylates

2′-5′ oligoadenylates are synthesized as described in U.S. Pat. Nos. 5,583,032 and 5,677,289.

EXAMPLE 14 Stereo-specific Synthesis of 2′-5′ Phosphorothioate Oligoadenylates

2′-5′ phosphorothioate oligoadenylates are synthesized in a stereo-specific manner as described in U.S. Pat. Nos. 4,924,624, 5,188,897, and 5,405,939.

EXAMPLE 15 Synthesis of 2′-5′ Xyloadenosine Oligonucleotides

2′-5′ xyloadenosine oligonucleotides are synthesized as described in U.S. Pat. No. 4,476,301.

EXAMPLE 16 Synthesis of 2′-5′ Oligoadenylate Analogues

2′-5′ oligoadenylate analogues are synthesized as described in U.S. Pat. No. 5,571,799.

EXAMPLE 17 2′,5′-Linked-3′-Deoxy Oligonucleotide Synthesis

The —O-(4,4′-dimethoxytrityl)-3′-deoxy-nucleoside-2′-[(2-cyanoethyl)-N,N-diisopropyl]phosphoramidites 1-4 were procured from Glen Research Inc. (Sterling, Va., USA).

A 0.1 M solution of the amidites 1-4 in anhydrous acetonitrile was used for the synthesis of modified oligonucleotides. The oligonucleotides were synthesized on functionalized controlled pore glass (CPG) on an automated solid phase DNA synthesizer. For incorporation of 3′-deoxy-nucleoside residues phosphoramidite solutions were delivered in two portions, each followed by a 3 min coupling wait time. All other steps in the protocol supplied by the manufacturer were used without modification. Oxidation of the internucleotide phosphite to the phosphate was carried out using 10% tert-butylhydroperoxide in acetonitrile with 10 min waiting time. Oligonucleotides were synthesized DMT on mode. The coupling efficiencies were more than 97%. After completion of the synthesis, the solid support was suspended in aqueous ammonium hydroxide (30 wt %, 2 mL for 2 micromole synthesis) and kept at room temperature for 2 h. The supernatant was decanted, the CPG was washed with additional 1 mL of aqueous ammonia. Combined ammonia solution was heated at 55° C. for 6 h, which concentrated the solution to half of the volume. The pH of the solution was adjusted to 8 and the crude oligonucleotides were purified by high performance liquid chromatography (HPLC, C-4 column, Waters, 7.8×300 mm, A=100 mM ammonium acetate, B=acetonitrile, 5-60% of B in 55 min, flow 2.5 mL min⁻¹, λ 260 nm). Fractions containing the full length oligonucleotides were pooled together and the pH of the solution was adjusted to 3.8 with acetic acid and kept at room temperature until the detritylation was complete. An aliquot was withdrawn and analyzed by HPLC on C-4 column using the conditions described above to assess the completion of the detritylation reaction. The solution was neutralized with ammonia and desalted by HPLC on a C-4 column to yield 3′-doxy oligonucleotides in 25-30% isolated yield. The oligonucleotides were characterized by ES MS and their purity was assessed by HPLC and Capillary Gel Electrophoresis.

TABLE 2 2′,5′-Linked-3′-deoxyoligonucleotides for siRNA mediated target reduction ISIS Back ES MS No sequence Bone Calcd Found 335389 5′ PO 6439.37 6439.8 d(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A* G*C*A*G* 2′ TT (SEQ ID NO: 7) 335390 5′ PO 6394.90 6393.6 d(C*U*G*C*T*A*G*C*C*T*C*T*G*G*A* T*T*T*G* 2′TT (SEQ ID NO: 8) T* = 3′-deoxy-5-methyluridine, A* = 3′-deoxyadenosine, G* = 3′-deoxyguanosine, C* = 3′-deoxycytidine, PO = phosphodiesters

EXAMPLE 18 2′,5′-Linked RNA Synthesis

The 5-O-(4,4′-dimethoxytrityl)-2′-O-(tert-butyldimethyl)silyl-nucleoside-2′-[(2-cyanoethyl)-N,N-diisopropyl]phosphoramidites 5-8 (below) were purchased from Chem Genes Corporation (Ashland, Mass., USA).

A 0.1 M solution of the amidites 5-8 in anhydrous acetonitrile was used for the synthesis of modified oligonucleotides. The oligonucleotides were synthesized on functionalized controlled pore glass (CPG) on an automated solid phase DNA synthesizer. For incorporation of modified-nucleoside residues phosphoramidite solutions were delivered in two portions, each followed by a 5 min coupling wait time. All other steps in the protocol supplied by the manufacturer were used without modification. Oxidation of the internucleotide phosphite to the phosphate was carried out using 10% tert-butylhydroperoxide in acetonitrile with 10 min waiting time. Oligonucleotides were synthesized using DMT off mode. The coupling efficiencies were more than 97%. After completion of the synthesis, solid support was suspended in aqueous ammonium hydroxide (30 wt. %):ethanol (3:1) and kept at room temperature for 2 h. The solid support was filtered and the filtrate was heated at 55° C. for 6 h to complete the removal of all protecting groups except the TBDMS group at 2′-position. The ammonia solution was lyophilized to dryness. The residue obtained was re-suspended in anhydrous TEA.HF/NMP/TEA solution (1 mL of a solution of 1.5 mL N-methylpyrrolidine, 750 μl TEA and 1 ml of TEA.3HF to provide a 1.4 M HF concentration) and heated at 65° C. for 1.5 h to remove the TBDMS groups at the 2′-position. The reaction was quenched with 1.5 M ammonium bicarbonate (1 mL) and the mixture was loaded on to a Sephadex G-25 column (NAP Columns, Amersham Biosciences Inc.). The oligonucleotides were eluted with water and the fractions containing the oligonucleotides were pooled together and purified by High Performance Liquid Chromatography (HPLC, Mono Q, Pharmacia Biotech, 16/10 (20 mL), 10 μm, ionic capacity 0.27-0.37 mmol/mL A=100 mM ammonium acetate, 30% aqueous acetonitrile pH=7, B=100 mM ammonium acetate, 1.5 M NaBr, 30% aqueous acetonitrile, 0 to 60% B in 40 min, Flow 2 mL min⁻¹, λ=260 nm). Fractions containing full-length oligonucleotides were pooled together (assessed by CGE analysis>90%) and evaporated. The residue was dissolved in sterile water (3 mL) and absolute ethanol (9 mL) was added and cooled in dry ice (−78° C.) for 1 h and the precipitate formed was pelleted out the by centrifugation (NYCentrifuge 5415C; Eppendorf, Westbury, N.Y.) at 3000 rpm (735 g). The supernatant was decanted and the pellet was re-dissolved in 10 M ammonium acetate (0.3 mL) solution. Ethanol (1 mL) was added and cooled to −78° C. for 1 h to get a precipitate and the precipitate was pelleted in a microfuge (NYCentrifuge 5415C; Eppendorf, Westbury, N.Y.) at 3000-rpm (735 g) for 15 min. The pellet was collected by decanting the supernatant. The pelleted oligonucleotides were dissolved in sterile water (0.3 mL) and precipitated by adding ethanol (1 mL) and cooling the mixture at −78° C. for 1 h. The precipitate formed was pelleted out and collected as described above. The oligonucleotides were characterized by ES MS analysis and purity was assessed by capillary gel electrophoresis and HPLC (Waters, C-18, 3.9×300 mm, A=100 mM triethylammonium acetate, pH=7, B=acetonitrile, 5 to 60% B in 40 min, Flow 1.5 mL min⁻¹, λ=260 nm).

TABLE 3 2′,5′-Linked-RNA for siRNA mediated target reduction ISIS Back ES MS No sequence Bone Calcd Found 345899 5′ PO 6715.28 6714.50 r(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A* G*C* A*G* 2′ TT (SEQ ID NO: 9) 345900 5′ PO 6600.48 6599.00 r(C*U*G*C*T*A*G*C*C*T*C*T*G*G*A*T *T* T*G* 2′TT (SEQ ID NO: 10) * = 2′,5′-linked , PO = phosphodiesters

EXAMPLE 19 Synthesis of Inverted Polarity Oligonucleotides

Inverted polarity oligonucleotides are synthesized as described in U.S. Pat. No. 5,399,676.

EXAMPLE 20 Synthesis of Chirally Pure Phosphorothioate Oligonucleotides

Enzymatic and chemical methods for synthesizing chirally pure phosphorothioate oligonucleotides are described in U.S. Pat. Nos. 5,506,212; 5,576,302; 5,587,361; 5,599,797; 5,607,923; 5,635,488; 5,661,134; and 5,582,188.

EXAMPLE 21 Synthesis of Chirally Pure Methylphosphonate, Phosphotriester, and Phosphoramidate Oligonucleotides

Chirally pure methylphosphonate, phosphotriester, and phosphoramidate oligonucleotides are synthesized as describes in U.S. Pat. Nos. 5,945,521 and 6,239,265.

EXAMPLE 22 Synthesis of Nucleoside Phosphoramidites

The following compounds, including amidites and their intermediates were prepared as described in U.S. Pat. No. 6,426,220 and published PCT WO 02/36743; 5′-O-Dimethoxytrityl-thymidine intermediate for 5-methyl dC amidite, 5′-O-Dimethoxytrityl-2′-deoxy-5-methylcytidine intermediate for 5-methyl-dC amidite, 5′-O-Dimethoxytrityl-2′-deoxy-N4-benzoyl-5-methylcytidine penultimate intermediate for 5-methyl dC amidite, [5′-O-(4,4′-Dimethoxytriphenylmethyl)-2′-deoxy-N⁴-benzoyl-5-methylcytidin-3′-O-yl]-2-cyanoethyl-N,N-diisopropylphosphoramidite (5-methyl dC amidite), 2′-Fluorodeoxyadenosine, 2′-Fluorodeoxyguanosine, 2′-Fluorouridine, 2′-Fluorodeoxycytidine, 2′-O-(2-Methoxyethyl) modified amidites, 2′-O-(2-methoxyethyl)-5-methyluridine intermediate, 5′-O-DMT-2′-O-(2-methoxyethyl)-5-methyluridine penultimate intermediate, [5′-O-(4,4′-Dimethoxytriphenylmethyl)-2′-O-(2-methoxyethyl)-5-methyluridin-3′-O-yl]-2-cyanoethyl-N,N-diisopropylphosphoramidite (MOE T amidite), 5′-O-Dimethoxytrityl-2′-O-(2-methoxyethyl)-5-methylcytidine intermediate, 5′-O-dimethoxytrityl-2′-O-(2-methoxyethyl)-N⁴-benzoyl-5-methyl-cytidine penultimate intermediate, [5′-O-(4,4′-Dimethoxytriphenylmethyl)-2′-O-(2-methoxyethyl)-N⁴-benzoyl-5-methylcytidin-3′-O-yl]-2-cyanoethyl-N,N-diisopropylphosphoramidite (MOE 5-Me-C amidite), [5′-O-(4,4′-Dimethoxytriphenylmethyl)-2′-O-(2-methoxyethyl)-N⁶-benzoyladenosin-3′-O-yl]-2-cyanoethyl-N,N-diisopropylphosphoramidite (MOE A amdite), [5′-O-(4,4′-Dimethoxytriphenylmethyl)-2′-O-(2-methoxyethyl)-N⁴-isobutyrylguanosin-3′-O-yl]-2-cyanoethyl-N,N-diisopropylphosphoramidite (MOE G amidite), 2′-O-(Aminooxyethyl) nucleoside amidites and 2′-O-(dimethylaminooxyethyl) nucleoside amidites, 2′-(Dimethylaminooxyethoxy) nucleoside amidites, 5′-O-tert-Butyldiphenylsilyl-O²-2′-anhydro-5-methyluridine, 5′-O-tert-Butyldiphenylsilyl-2′-O-(2-hydroxyethyl)-5-methyluridine, 2′-O-([2-phthalimidoxy)ethyl]-5′-t-butyldiphenylsilyl-5-methyluridine, 5′-O-tert-butyldiphenylsilyl-2′-O-[(2-formadoximinooxy)ethyl]-5-methyluridine, 5′-O-tert-Butyldiphenylsilyl-2′-O—[N,N dimethylaminooxyethyl]-5-methyluridine, 2′-O-(dimethylaminooxyethyl)-5-methyluridine, 5′-O-DMT-2′-O-(dimethylaminooxyethyl)-5-methyluridine, 5′-O-DMT-2′-O-(2-N,N-dimethylaminooxyethyl)-5-methyluridine-3′-[(2-cyanoethyl)-N,N-diisopropylphosphoramidite], 2′-(Aminooxyethoxy) nucleoside amidites, N2-isobutyryl-6-O-diphenylcarbamoyl-2′-O-(2-ethylacetyl)-5′-O-(4,4′-dimethoxytrityl)guanosine-3′-[(2-cyanoethyl)-N,N-diisopropylphosphoramidite], 2′-dimethylaminoethoxyethoxy (2′-DMAEOE) nucleoside amidites, 2′-O-[2(2-N,N-dimethylaminoethoxy)ethyl]-5-methyl uridine, 5′-O-dimethoxytrityl-2′-O-[2(2-N,N-dimethylaminoethoxy)-ethyl)]-5-methyl uridine and 5′-O-Dimethoxytrityl-2′-O-[2(2-N,N-dimethylaminoethoxy)-ethyl)]-5-methyl uridine-3′-O-(cyanoethyl-N,N-diisopropyl)phosphoramidite.

EXAMPLE 23 Oligonucleoside Synthesis

Methylenemethylimino linked oligonucleosides, also identified as MMI linked oligonucleosides, methylenedimethylhydrazo linked oligonucleosides, also identified as MDH linked oligonucleosides, and methylenecarbonylamino linked oligonucleosides, also identified as amide-3 linked oligonucleosides, and methyleneaminocarbonyl linked oligonucleosides, also identified as amide-4 linked oligonucleosides, as well as mixed backbone oligomeric compounds having, for instance, alternating MMI and P═O or P═S linkages are prepared as described in U.S. Pat. Nos. 5,378,825, 5,386,023, 5,489,677, 5,602,240 and 5,610,289, all of which are herein incorporated by reference.

Formacetal and thioformacetal linked oligonucleosides are prepared as described in U.S. Pat. Nos. 5,264,562 and 5,264,564, herein incorporated by reference.

Ethylene oxide linked oligonucleosides are prepared as described in U.S. Pat. No. 5,223,618, herein incorporated by reference.

EXAMPLE 24 RNA Synthesis

In general, RNA synthesis chemistry is based on the selective incorporation of various protecting groups at strategic intermediary reactions. Although one of ordinary skill in the art will understand the use of protecting groups in organic synthesis, a useful class of protecting groups includes silyl ethers. In particular bulky silyl ethers are used to protect the 5′-hydroxyl in combination with an acid-labile orthoester protecting group on the 2′-hydroxyl. This set of protecting groups is then used with standard solid-phase synthesis technology. It is important to lastly remove the acid labile orthoester protecting group after all other synthetic steps. Moreover, the early use of the silyl protecting groups during synthesis ensures facile removal when desired, without undesired deprotection of 2′ hydroxyl.

Following this procedure for the sequential protection of the 5′-hydroxyl in combination with protection of the 2′-hydroxyl by protecting groups that are differentially removed and are differentially chemically labile, RNA oligonucleotides were synthesized.

RNA oligonucleotides are synthesized in a stepwise fashion. Each nucleotide is added sequentially (3′- to 5′-direction) to a solid support-bound oligonucleotide. The first nucleoside at the 3′-end of the chain is covalently attached to a solid support. The nucleotide precursor, a ribonucleoside phosphoramidite, and activator are added, coupling the second base onto the 5′-end of the first nucleoside. The support is washed and any unreacted 5′-hydroxyl groups are capped with acetic anhydride to yield 5′-acetyl moieties. The linkage is then oxidized to the more stable and ultimately desired P(V) linkage. At the end of the nucleotide addition cycle, the 5′-silyl group is cleaved with fluoride. The cycle is repeated for each subsequent nucleotide.

Following synthesis, the methyl protecting groups on the phosphates are cleaved in 30 minutes utilizing 1 M disodium-2-carbamoyl-2-cyanoethylene-1,1-dithiolate trihydrate (S₂Na₂) in DMF. The deprotection solution is washed from the solid support-bound oligonucleotide using water. The support is then treated with 40% methylamine in water for 10 minutes at 55° C. This releases the RNA oligonucleotides into solution, deprotects the exocyclic amines, and modifies the 2′-groups. The oligonucleotides can be analyzed by anion exchange HPLC at this stage.

The 2′-orthoester groups are the last protecting groups to be removed. The ethylene glycol monoacetate orthoester protecting group developed by Dharmacon Research, Inc. (Lafayette, Colo.), is one example of a useful orthoester protecting group which, has the following important properties. It is stable to the conditions of nucleoside phosphoramidite synthesis and oligonucleotide synthesis. However, after oligonucleotide synthesis the oligonucleotide is treated with methylamine which not only cleaves the oligonucleotide from the solid support but also removes the acetyl groups from the orthoesters. The resulting 2-ethyl-hydroxyl substituents on the orthoester are less electron withdrawing than the acetylated precursor. As a result, the modified orthoester becomes more labile to acid-catalyzed hydrolysis. Specifically, the rate of cleavage is approximately 10 times faster after the acetyl groups are removed. Therefore, this orthoester possesses sufficient stability in order to be compatible with oligonucleotide synthesis and yet, when subsequently modified, permits deprotection to be carried out under relatively mild aqueous conditions compatible with the final RNA oligonucleotide product.

Additionally, methods of RNA synthesis are well known in the art (Scaringe, S. A. Ph.D. Thesis, University of Colorado, 1996; Scaringe, S. A., et al., J. Am. Chem. Soc., 1998, 120, 11820-11821; Matteucci, M. D. and Caruthers, M. H. J. Am. Chem. Soc., 1981, 103, 3185-3191; Beaucage, S. L. and Caruthers, M. H. Tetrahedron Lett., 1981, 22, 1859-1862; Dahl, B. J., et al., Acta Chem. Scand., 1990, 44, 639-641; Reddy, M. P., et al., Tetrahedrom Lett., 1994, 25, 4311-4314; Wincott, F. et al., Nucleic Acids Res., 1995, 23, 2677-2684; Griffin, B. E., et al., Tetrahedron, 1967, 23, 2301-2313; Griffin, B. E., et al., Tetrahedron, 1967, 23, 2315-2331).

EXAMPLE 25 Synthesis of Chimeric Oligonucleotides

Chimeric oligonucleotides, oligonucleosides or mixed oligonucleotides/oligonucleosides of the invention can be of several different types. These include a first type wherein the “gap” segment of linked nucleosides is positioned between 5′ and 3′ “wing” segments of linked nucleosides and a second “open end” type wherein the “gap” segment is located at either the 3′ or the 5′ terminus of the oligomeric compound. Oligonucleotides of the first type are also known in the art as “gapmers” or gapped oligonucleotides. Oligonucleotides of the second type are also known in the art as “hemimers” or “wingmers”.

[2′-O-Me]--[2′-Deoxy]--[2′-O-Me] Chimeric Phosphorothioate Oligonucleotides

Chimeric oligonucleotides having 2′-O-alkyl phosphorothioate and 2′-deoxy phosphorothioate oligonucleotide segments are synthesized using an Applied Biosystems automated DNA synthesizer Model 394, as above. Oligonucleotides are synthesized using the automated synthesizer and 2′-deoxy-5′-dimethoxytrityl-3′-O-phosphoramidite for the DNA portion and 5′-dimethoxytrityl-2′-O-methyl-3′-O-phosphoramidite for 5′ and 3′ wings. The standard synthesis cycle is modified by incorporating coupling steps with increased reaction times for the 5′-dimethoxytrityl-2′-O-methyl-3′-O-phosphoramidite. The fully protected oligonucleotide is cleaved from the support and deprotected in concentrated ammonia (NH₄OH) for 12-16 hr at 55° C. The deprotected oligo is then recovered by an appropriate method (precipitation, column chromatography, volume reduced in vacuo and analyzed spectrophotometrically for yield and for purity by capillary electrophoresis and by mass spectrometry.

[2′-O-(2-Methoxyethyl)]--[2′-deoxy]--[2′-O-(Methoxyethyl)] Chimeric Phosphorothioate Oligonucleotides

[2′-O-(2-methoxyethyl)]--[2′-deoxy]--[-2′-O-(methoxyethyl)] chimeric phosphorothioate oligonucleotides were prepared as per the procedure above for the 2′-O-methyl chimeric oligonucleotide, with the substitution of 2′-O-(methoxyethyl) amidites for the 2′-O-methyl amidites.

[2′-O-(2-Methoxyethyl)Phosphodiester]--[2′-deoxy Phosphorothioate]--[2′-O-(2-Methoxyethyl)Phosphodiester] Chimeric Oligonucleotides

[2′-O-(2-methoxyethyl phosphodiester]--[2′-deoxy phosphorothioate]--[2′-O-(methoxyethyl)phosphodiester] chimeric oligonucleotides are prepared as per the above procedure for the 2′-O-methyl chimeric oligonucleotide with the substitution of 2′-O-(methoxyethyl) amidites for the 2′-O-methyl amidites, oxidation with iodine to generate the phosphodiester internucleotide linkages within the wing portions of the chimeric structures and sulfurization utilizing 3,H-1,2 benzodithiole-3-one 1,1 dioxide (Beaucage Reagent) to generate the phosphorothioate internucleotide linkages for the center gap.

Other chimeric oligonucleotides, chimeric oligonucleosides and mixed chimeric oligonucleotides/oligonucleosides are synthesized according to U.S. Pat. No. 5,623,065, herein incorporated by reference.

EXAMPLE 26 Design and Screening of Duplexed Oligomeric Compounds Targeting a Target

In accordance with the present invention, a series of nucleic acid duplexes comprising the antisense oligomeric compounds of the present invention and their complements can be designed to target a target. The ends of the strands may be modified by the addition of one or more natural or modified nucleobases to form an overhang. The sense strand of the dsRNA is then designed and synthesized as the complement of the antisense strand and may also contain modifications or additions to either terminus. For example, in one embodiment, both strands of the dsRNA duplex would be complementary over the central nucleobases, each having overhangs at one or both termini.

For example, a duplex comprising an antisense strand having the sequence CGAGAGGCGGACGGGACCG (SEQ ID NO:1) and having a two-nucleobase overhang of deoxythymidine(dT) would have the following structure:

5′     c g a g a g g c g g a c g g g a c c g T T 3′ Antisense Strand (SEQ ID NO: 2)        | | | | | | | | | | | | | | | | | | | 3′ T T g c t c t c c g c c t g c c c t g g c     5′ Complement Strand (SEQ ID NO: 3)

RNA strands of the duplex can be synthesized by methods disclosed herein or purchased from Dharmacon Research Inc., (Lafayette, Colo.). Once synthesized, the complementary strands are annealed. The single strands are aliquoted and diluted to a concentration of 50 uM. Once diluted, 30 uL of each strand is combined with 15 uL of a 5× solution of annealing buffer. The final concentration of said buffer is 100 mM potassium acetate, 30 mM HEPES-KOH pH 7.4, and 2 mM magnesium acetate. The final volume is 75 uL. This solution is incubated for 1 minute at 90° C. and then centrifuged for 15 seconds. The tube is allowed to sit for 1 hour at 37° C. at which time the dsRNA duplexes are used in experimentation. The final concentration of the dsRNA duplex is 20 uM. This solution can be stored frozen (−20° C.) and freeze-thawed up to 5 times.

Once prepared, the duplexed antisense oligomeric compounds are evaluated for their ability to modulate a target expression.

When cells reached 80% confluency, they are treated with duplexed antisense oligomeric compounds of the invention. For cells grown in 96-well plates, wells are washed once with 200 μL, OPTI-MEM-1 reduced-serum medium (Gibco BRL) and then treated with 130 μL, of OPTI-MEM-1 containing 12 μg/mL LIPOFECTIN (Gibco BRL) and the desired duplex antisense oligomeric compound at a final concentration of 200 nM. After 5 hours of treatment, the medium is replaced with fresh medium. Cells are harvested 16 hours after treatment, at which time RNA is isolated and target reduction measured by RT-PCR.

EXAMPLE 27 Oligonucleotide Isolation

After cleavage from the controlled pore glass solid support and deblocking in concentrated ammonium hydroxide at 55° C. for 12-16 hours, the oligonucleotides or oligonucleosides are recovered by precipitation out of 1 M NH₄OAc with >3 volumes of ethanol. Synthesized oligonucleotides were analyzed by electrospray mass spectroscopy (molecular weight determination) and by capillary gel electrophoresis and judged to be at least 70% full length material. The relative amounts of phosphorothioate and phosphodiester linkages obtained in the synthesis was determined by the ratio of correct molecular weight relative to the −16 amu product (+/−32+/−48). For some studies oligonucleotides were purified by HPLC, as described by Chiang et al., J. Biol. Chem. 1991, 266, 18162-18171. Results obtained with HPLC-purified material were similar to those obtained with non-HPLC purified material.

EXAMPLE 28 Oligonucleotide Synthesis—96 Well Plate Format

Oligonucleotides were synthesized via solid phase P(III) phosphoramidite chemistry on an automated synthesizer capable of assembling 96 sequences simultaneously in a 96-well format. Phosphodiester internucleotide linkages were afforded by oxidation with aqueous iodine. Phosphorothioate internucleotide linkages were generated by sulfurization utilizing 3,H-1,2 benzodithiole-3-one 1,1 dioxide (Beaucage Reagent) in anhydrous acetonitrile. Standard base-protected beta-cyanoethyl-diiso-propyl phosphoramidites were purchased from commercial vendors (e.g. PE-Applied Biosystems, Foster City, Calif., or Pharmacia, Piscataway, N.J.). Non-standard nucleosides are synthesized as per standard or patented methods. They are utilized as base protected beta-cyanoethyldiisopropyl phosphoramidites.

Oligonucleotides were cleaved from support and deprotected with concentrated NH₄OH at elevated temperature (55-60° C.) for 12-16 hours and the released product then dried in vacuo. The dried product was then re-suspended in sterile water to afford a master plate from which all analytical and test plate samples are then diluted utilizing robotic pipettors.

EXAMPLE 29 Oligonucleotide Analysis—96-Well Plate Format

The concentration of oligonucleotide in each well was assessed by dilution of samples and UV absorption spectroscopy. The full-length integrity of the individual products was evaluated by capillary electrophoresis (CE) in either the 96-well format (Beckman P/ACE™ MDQ) or, for individually prepared samples, on a commercial CE apparatus (e.g., Beckman P/ACE™ 5000, ABI 270). Base and backbone composition was confirmed by mass analysis of the oligomeric compounds utilizing electrospray-mass spectroscopy. All assay test plates were diluted from the master plate using single and multi-channel robotic pipettors. Plates were judged to be acceptable if at least 85% of the oligomeric compounds on the plate were at least 85% full length.

EXAMPLE 30 Cell Culture and Oligonucleotide Treatment

The effect of oligomeric compounds on target nucleic acid expression can be tested in any of a variety of cell types provided that the target nucleic acid is present at measurable levels. This can be routinely determined using, for example, PCR or Northern blot analysis. The following cell types are provided for illustrative purposes, but other cell types can be routinely used, provided that the target is expressed in the cell type chosen. This can be readily determined by methods routine in the art, for example Northern blot analysis, ribonuclease protection assays, or RT-PCR.

T-24 Cells:

The human transitional cell bladder carcinoma cell line T-24 was obtained from the American Type Culture Collection (ATCC) (Manassas, Va.). T-24 cells were routinely cultured in complete McCoy's 5A basal media (Invitrogen Corporation, Carlsbad, Calif.) supplemented with 10% fetal calf serum (Invitrogen Corporation, Carlsbad, Calif.), penicillin 100 units per mL, and streptomycin 100 micrograms per mL (Invitrogen Corporation, Carlsbad, Calif.). Cells were routinely passaged by trypsinization and dilution when they reached 90% confluence. Cells were seeded into 96-well plates (Falcon-Primaria #353872) at a density of 7000 cells/well for use in RT-PCR analysis.

For Northern blotting or other analysis, cells may be seeded onto 100 mm or other standard tissue culture plates and treated similarly, using appropriate volumes of medium and oligonucleotide.

A549 Cells:

The human lung carcinoma cell line A549 was obtained from the American Type Culture Collection (ATCC) (Manassas, Va.). A549 cells were routinely cultured in DMEM basal media (Invitrogen Corporation, Carlsbad, Calif.) supplemented with 10% fetal calf serum (Invitrogen Corporation, Carlsbad, Calif.), penicillin 100 units per mL, and streptomycin 100 micrograms per mL (Invitrogen Corporation, Carlsbad, Calif.). Cells were routinely passaged by trypsinization and dilution when they reached 90% confluence.

NHDF Cells:

Human neonatal dermal fibroblast (NHDF) were obtained from the Clonetics Corporation (Walkersville, Md.). NHDFs were routinely maintained in Fibroblast Growth Medium (Clonetics Corporation, Walkersville, Md.) supplemented as recommended by the supplier. Cells were maintained for up to 10 passages as recommended by the supplier.

HEK Cells:

Human embryonic keratinocytes (HEK) were obtained from the Clonetics Corporation (Walkersville, Md.). HEKs were routinely maintained in Keratinocyte Growth Medium (Clonetics Corporation, Walkersville, Md.) formulated as recommended by the supplier. Cells were routinely maintained for up to 10 passages as recommended by the supplier.

Treatment with Antisense Oligomeric Compounds:

When cells reached 65-75% confluency, they were treated with oligonucleotide. For cells grown in 96-well plates, wells were washed once with 100 μL OPTI-MEM™-1 reduced-serum medium (Invitrogen Corporation, Carlsbad, Calif.) and then treated with 130 μL of OPTI-MEM™-1 containing 3.75 μg/mL LIPOFECTIN™ (Invitrogen Corporation, Carlsbad, Calif.) and the desired concentration of oligonucleotide. Cells are treated and data are obtained in triplicate. After 4-7 hours of treatment at 37° C., the medium was replaced with fresh medium. Cells were harvested 16-24 hours after oligonucleotide treatment.

The concentration of oligonucleotide used varies from cell line to cell line. To determine the optimal oligonucleotide concentration for a particular cell line, the cells are treated with a positive control oligonucleotide at a range of concentrations. For human cells the positive control oligonucleotide is selected from either ISIS 13920 (TCCGTCATCGCTCCTCAGGG, SEQ ID NO: 4) which is targeted to human H-ras, or ISIS 18078, (GTGCGCGCGAGCCCGAAATC, SEQ ID NO: 5) which is targeted to human Jun-N-terminal kinase-2 (JNK2). Both controls are 2′-O-methoxyethyl gapmers (2′-O-methoxyethyls shown in bold) with a phosphorothioate backbone. For mouse or rat cells the positive control oligonucleotide is ISIS 15770, ATGCATTCTGCCCCCAAGGA (SEQ ID NO: 6) a 2′-O-methoxyethyl gapmer (2′-O-methoxyethyls shown in bold) with a phosphorothioate backbone which is targeted to both mouse and rat c-raf. The concentration of positive control oligonucleotide that results in 80% inhibition of c-H-ras (for ISIS 13920), JNK2 (for ISIS 18078) or c-raf (for ISIS 15770) mRNA is then utilized as the screening concentration for new oligonucleotides in subsequent experiments for that cell line. If 80% inhibition is not achieved, the lowest concentration of positive control oligonucleotide that results in 60% inhibition of c-H-ras, JNK2 or c-raf mRNA is then utilized as the oligonucleotide screening concentration in subsequent experiments for that cell line. If 60% inhibition is not achieved, that particular cell line is deemed as unsuitable for oligonucleotide transfection experiments. The concentrations of antisense oligonucleotides used herein are from 50 nM to 300 nM.

EXAMPLE 31 Analysis of Oligonucleotide Inhibition of a Target Expression

Modulation of a target expression can be assayed in a variety of ways known in the art. For example, a target mRNA levels can be quantitated by, e.g., Northern blot analysis, competitive polymerase chain reaction (PCR), or real-time PCR (RT-PCR). Real-time quantitative PCR is presently preferred. RNA analysis can be performed on total cellular RNA or poly(A)+mRNA. The preferred method of RNA analysis of the present invention is the use of total cellular RNA as described in other examples herein. Methods of RNA isolation are well known in the art. Northern blot analysis is also routine in the art. Real-time quantitative (PCR) can be conveniently accomplished using the commercially available ABI PRISM™ 7600, 7700, or 7900 Sequence Detection System, available from PE-Applied Biosystems, Foster City, Calif. and used according to manufacturer's instructions.

Protein levels of a target can be quantitated in a variety of ways well known in the art, such as immunoprecipitation, Western blot analysis (immunoblotting), enzyme-linked immunosorbent assay (ELISA) or fluorescence-activated cell sorting (FACS). Antibodies directed to a target can be identified and obtained from a variety of sources, such as the MSRS catalog of antibodies (Aerie Corporation, Birmingham, Mich.), or can be prepared via conventional monoclonal or polyclonal antibody generation methods well known in the art.

EXAMPLE 32 Design of Phenotypic Assays and In Vivo Studies for the Use of a Target Inhibitors

Phenotypic Assays

Once a target inhibitors have been identified by the methods disclosed herein, the oligomeric compounds are further investigated in one or more phenotypic assays, each having measurable endpoints predictive of efficacy in the treatment of a particular disease state or condition.

Phenotypic assays, kits and reagents for their use are well known to those skilled in the art and are herein used to investigate the role and/or association of a target in health and disease. Representative phenotypic assays, which can be purchased from any one of several commercial vendors, include those for determining cell viability, cytotoxicity, proliferation or cell survival (Molecular Probes, Eugene, Oreg.; PerkinElmer, Boston, Mass.), protein-based assays including enzymatic assays (Panvera, LLC, Madison, Wis.; BD Biosciences, Franklin Lakes, N.J.; Oncogene Research Products, San Diego, Calif.), cell regulation, signal transduction, inflammation, oxidative processes and apoptosis (Assay Designs Inc., Ann Arbor, Mich.), triglyceride accumulation (Sigma-Aldrich, St. Louis, Mo.), angiogenesis assays, tube formation assays, cytokine and hormone assays and metabolic assays (Chemicon International Inc., Temecula, Calif.; Amersham Biosciences, Piscataway, N.J.).

In one non-limiting example, cells determined to be appropriate for a particular phenotypic assay (i.e., MCF-7 cells selected for breast cancer studies; adipocytes for obesity studies) are treated with a target inhibitors identified from the in vitro studies as well as control compounds at optimal concentrations which are determined by the methods described above. At the end of the treatment period, treated and untreated cells are analyzed by one or more methods specific for the assay to determine phenotypic outcomes and endpoints.

Phenotypic endpoints include changes in cell morphology over time or treatment dose as well as changes in levels of cellular components such as proteins, lipids, nucleic acids, hormones, saccharides or metals. Measurements of cellular status which include pH, stage of the cell cycle, intake or excretion of biological indicators by the cell, are also endpoints of interest.

Analysis of the genotype of the cell (measurement of the expression of one or more of the genes of the cell) after treatment is also used as an indicator of the efficacy or potency of the target inhibitors. Hallmark genes, or those genes suspected to be associated with a specific disease state, condition, or phenotype, are measured in both treated and untreated cells.

In Vivo Studies

The individual subjects of the in vivo studies described herein are warm-blooded vertebrate animals, which includes humans.

The clinical trial is subjected to rigorous controls to ensure that individuals are not unnecessarily put at risk and that they are fully informed about their role in the study.

To account for the psychological effects of receiving treatments, volunteers are randomly given placebo or a target inhibitor. Furthermore, to prevent the doctors from being biased in treatments, they are not informed as to whether the medication they are administering is a a target inhibitor or a placebo. Using this randomization approach, each volunteer has the same chance of being given either the new treatment or the placebo.

Volunteers receive either the a target inhibitor or placebo for eight week period with biological parameters associated with the indicated disease state or condition being measured at the beginning (baseline measurements before any treatment), end (after the final treatment), and at regular intervals during the study period. Such measurements include the levels of nucleic acid molecules encoding a target or a target protein levels in body fluids, tissues or organs compared to pre-treatment levels. Other measurements include, but are not limited to, indices of the disease state or condition being treated, body weight, blood pressure, serum titers of pharmacologic indicators of disease or toxicity as well as ADME (absorption, distribution, metabolism and excretion) measurements.

Information recorded for each patient includes age (years), gender, height (cm), family history of disease state or condition (yes/no), motivation rating (some/moderate/great) and number and type of previous treatment regimens for the indicated disease or condition.

Volunteers taking part in this study are healthy adults (age 18 to 65 years) and roughly an equal number of males and females participate in the study. Volunteers with certain characteristics are equally distributed for placebo and a target inhibitor treatment. In general, the volunteers treated with placebo have little or no response to treatment, whereas the volunteers treated with the target inhibitor show positive trends in their disease state or condition index at the conclusion of the study.

EXAMPLE 33 RNA Isolation

Poly(A)+mRNA Isolation

Poly(A)+mRNA was isolated according to Miura et al., (Clin. Chem., 1996, 42, 1758-1764). Other methods for poly(A)+mRNA isolation are routine in the art. Briefly, for cells grown on 96-well plates, growth medium was removed from the cells and each well was washed with 200 μL cold PBS. 60 μL lysis buffer (10 mM Tris-HCl, pH 7.6, 1 mM EDTA, 0.5 M NaCl, 0.5% NP-40, 20 mM vanadyl-ribonucleoside complex) was added to each well, the plate was gently agitated and then incubated at room temperature for five minutes. 55 μL of lysate was transferred to Oligo d(T) coated 96-well plates (AGCT Inc., Irvine Calif.). Plates were incubated for 60 minutes at room temperature, washed 3 times with 200 μL of wash buffer (10 mM Tris-HCl pH 7.6, 1 mM EDTA, 0.3 M NaCl). After the final wash, the plate was blotted on paper towels to remove excess wash buffer and then air-dried for 5 minutes. 60 μL of elution buffer (5 mM Tris-HCl pH 7.6), preheated to 70° C., was added to each well, the plate was incubated on a 90° C. hot plate for 5 minutes, and the eluate was then transferred to a fresh 96-well plate.

Cells grown on 100 mm or other standard plates may be treated similarly, using appropriate volumes of all solutions.

Total RNA Isolation

Total RNA was isolated using an RNEASY 96™ kit and buffers purchased from Qiagen Inc. (Valencia, Calif.) following the manufacturer's recommended procedures. Briefly, for cells grown on 96-well plates, growth medium was removed from the cells and each well was washed with 200 μL cold PBS. 150 μL Buffer RLT was added to each well and the plate vigorously agitated for 20 seconds. 150 μL of 70% ethanol was then added to each well and the contents mixed by pipetting three times up and down. The samples were then transferred to the RNEASY 96™ well plate attached to a QIAVAC™ manifold fitted with a waste collection tray and attached to a vacuum source. Vacuum was applied for 1 minute. 500 μL of Buffer RW1 was added to each well of the RNEASY 96™ plate and incubated for 15 minutes and the vacuum was again applied for 1 minute. An additional 500 μL of Buffer RW1 was added to each well of the RNEASY 96™ plate and the vacuum was applied for 2 minutes. 1 mL of Buffer RPE was then added to each well of the RNEASY 96™ plate and the vacuum applied for a period of 90 seconds. The Buffer RPE wash was then repeated and the vacuum was applied for an additional 3 minutes. The plate was then removed from the QIAVAC™ manifold and blotted dry on paper towels. The plate was then re-attached to the QIAVAC™ manifold fitted with a collection tube rack containing 1.2 mL collection tubes. RNA was then eluted by pipetting 140 μL of RNAse free water into each well, incubating 1 minute, and then applying the vacuum for 3 minutes.

The repetitive pipetting and elution steps may be automated using a QIAGEN BioRobot 9604 (Qiagen, Inc., Valencia Calif.). Essentially, after lysing of the cells on the culture plate, the plate is transferred to the robot deck where the pipetting, DNase treatment and elution steps are carried out.

EXAMPLE 34 Real-time Quantitative PCR Analysis of a Target mRNA Levels

Quantitation of a target mRNA levels was accomplished by real-time quantitative PCR using the ABI PRISM™ 7600, 7700, or 7900 Sequence Detection System (PE-Applied Biosystems, Foster City, Calif.) according to manufacturer's instructions. This is a closed-tube, non-gel-based, fluorescence detection system which allows high-throughput quantitation of polymerase chain reaction (PCR) products in real-time. As opposed to standard PCR in which amplification products are quantitated after the PCR is completed, products in real-time quantitative PCR are quantitated as they accumulate. This is accomplished by including in the PCR reaction an oligonucleotide probe that anneals specifically between the forward and reverse PCR primers, and contains two fluorescent dyes. A reporter dye (e.g., FAM or JOE, obtained from either PE-Applied Biosystems, Foster City, Calif., Operon Technologies Inc., Alameda, Calif. or Integrated DNA Technologies Inc., Coralville, Iowa) is attached to the 5′ end of the probe and a quencher dye (e.g., TAMRA, obtained from either PE-Applied Biosystems, Foster City, Calif., Operon Technologies Inc., Alameda, Calif. or Integrated DNA Technologies Inc., Coralville, Iowa) is attached to the 3′ end of the probe. When the probe and dyes are intact, reporter dye emission is quenched by the proximity of the 3′ quencher dye. During amplification, annealing of the probe to the target sequence creates a substrate that can be cleaved by the 5′-exonuclease activity of Taq polymerase. During the extension phase of the PCR amplification cycle, cleavage of the probe by Taq polymerase releases the reporter dye from the remainder of the probe (and hence from the quencher moiety) and a sequence-specific fluorescent signal is generated. With each cycle, additional reporter dye molecules are cleaved from their respective probes, and the fluorescence intensity is monitored at regular intervals by laser optics built into the ABI PRISM™ Sequence Detection System. In each assay, a series of parallel reactions containing serial dilutions of mRNA from untreated control samples generates a standard curve that is used to quantitate the percent inhibition after antisense oligonucleotide treatment of test samples.

Prior to quantitative PCR analysis, primer-probe sets specific to the target gene being measured are evaluated for their ability to be “multiplexed” with a GAPDH amplification reaction. In multiplexing, both the target gene and the internal standard gene GAPDH are amplified concurrently in a single sample. In this analysis, mRNA isolated from untreated cells is serially diluted. Each dilution is amplified in the presence of primer-probe sets specific for GAPDH only, target gene only (“single-plexing”), or both (multiplexing). Following PCR amplification, standard curves of GAPDH and target mRNA signal as a function of dilution are generated from both the single-plexed and multiplexed samples. If both the slope and correlation coefficient of the GAPDH and target signals generated from the multiplexed samples fall within 10% of their corresponding values generated from the single-plexed samples, the primer-probe set specific for that target is deemed multiplexable. Other methods of PCR are also known in the art.

PCR reagents were obtained from Invitrogen Corporation, (Carlsbad, Calif.). RT-PCR reactions were carried out by adding 20 μL PCR cocktail (2.5×PCR buffer minus MgCl₂, 6.6 mM MgCl₂, 375 μM each of dATP, dCTP, dCTP and dGTP, 375 nM each of forward primer and reverse primer, 125 nM of probe, 4 Units RNAse inhibitor, 1.25 Units PLATINUM® Taq, 5 Units MuLV reverse transcriptase, and 2.5×ROX dye) to 96-well plates containing 30 μL total RNA solution (20-200 ng). The RT reaction was carried out by incubation for 30 minutes at 48° C. Following a 10 minute incubation at 95° C. to activate the PLATINUM® Taq, 40 cycles of a two-step PCR protocol were carried out: 95° C. for 15 seconds (denaturation) followed by 60° C. for 1.5 minutes (annealing/extension).

Gene target quantities obtained by real time RT-PCR are normalized using either the expression level of GAPDH, a gene whose expression is constant, or by quantifying total RNA using RiboGreen™ (Molecular Probes, Inc. Eugene, Oreg.). GAPDH expression is quantified by real time RT-PCR, by being run simultaneously with the target, multiplexing, or separately. Total RNA is quantified using RiboGreen™ RNA quantification reagent (Molecular Probes, Inc. Eugene, Oreg.). Methods of RNA quantification by RiboGreen™ are taught in Jones, L. J., et al, (Analytical Biochemistry, 1998, 265, 368-374).

In this assay, 170 μL of RiboGreen™ working reagent (RiboGreen™ reagent diluted 1:350 in 10 mM Tris-HCl, 1 mM EDTA, pH 7.5) is pipetted into a 96-well plate containing 30 μL purified, cellular RNA. The plate is read in a CytoFluor 4000 (PE Applied Biosystems) with excitation at 485 nm and emission at 530 nm.

Probes and primers are designed to hybridize to a human a target sequence, using published sequence information.

EXAMPLE 35 Northern Blot Analysis of a Target mRNA Levels

Eighteen hours after treatment, cell monolayers were washed twice with cold PBS and lysed in 1 mL RNAZOL™ (TEL-TEST “B” Inc., Friendswood, Tex.). Total RNA was prepared following manufacturer's recommended protocols. Twenty micrograms of total RNA was fractionated by electrophoresis through 1.2% agarose gels containing 1.1% formaldehyde using a MOPS buffer system (AMRESCO, Inc. Solon, Ohio). RNA was transferred from the gel to HYBOND™-N+ nylon membranes (Amersham Pharmacia Biotech, Piscataway, N.J.) by overnight capillary transfer using a Northern/Southern Transfer buffer system (TEL-TEST “B” Inc., Friendswood, Tex.). RNA transfer was confirmed by UV visualization. Membranes were fixed by UV cross-linking using a STRATALINKER™ UV Crosslinker 2400 (Stratagene, Inc, La Jolla, Calif.) and then probed using QUICKHYB™ hybridization solution (Stratagene, La Jolla, Calif.) using manufacturer's recommendations for stringent conditions.

To detect human a target, a human a target specific primer probe set is prepared by PCR To normalize for variations in loading and transfer efficiency membranes are stripped and probed for human glyceraldehyde-3-phosphate dehydrogenase (GAPDH) RNA (Clontech, Palo Alto, Calif.).

Hybridized membranes were visualized and quantitated using a PHOSPHORIMAGER™ and IMAGEQUANT™ Software V3.3 (Molecular Dynamics, Sunnyvale, Calif.). Data was normalized to GAPDH levels in untreated controls.

EXAMPLE 36 Inhibition of Human a Target Expression by Oligonucleotides

In accordance with the present invention, a series of oligomeric compounds are designed to target different regions of the human target RNA. The oligomeric compounds are analyzed for their effect on human target mRNA levels by quantitative real-time PCR as described in other examples herein. Data are averages from three experiments. The target regions to which these preferred sequences are complementary are herein referred to as “preferred target segments” and are therefore preferred for targeting by oligomeric compounds of the present invention. The sequences represent the reverse complement of the preferred antisense oligomeric compounds.

As these “preferred target segments” have been found by experimentation to be open to, and accessible for, hybridization with the antisense oligomeric compounds of the present invention, one of skill in the art will recognize or be able to ascertain, using no more than routine experimentation, further embodiments of the invention that encompass other oligomeric compounds that specifically hybridize to these preferred target segments and consequently inhibit the expression of a target.

According to the present invention, antisense oligomeric compounds include antisense oligomeric compounds, antisense oligonucleotides, ribozymes, external guide sequence (EGS) oligonucleotides, alternate splicers, primers, probes, and other short oligomeric compounds that hybridize to at least a portion of the target nucleic acid.

EXAMPLE 37 Western Blot Analysis of a Target Protein Levels

Western blot analysis (immunoblot analysis) is carried out using standard methods. Cells are harvested 16-20 h after oligonucleotide treatment, washed once with PBS, suspended in Laemmli buffer (100 ul/well), boiled for 5 minutes and loaded on a 16% SDS-PAGE gel. Gels are run for 1.5 hours at 150 V, and transferred to membrane for western blotting. Appropriate primary antibody directed to a target is used, with a radiolabeled or fluorescently labeled secondary antibody directed against the primary antibody species. Bands are visualized using a PHOSPHORIMAGER™ (Molecular Dynamics, Sunnyvale Calif.).

EXAMPLE 38 siRNA-Mediated Inhibition of PTEN Message: Effect of 2′,5′-linked 3′-deoxyoligonucleotide Constructs on PTEN mRNA Expression

siRNA Duplex Formation: Synthetic siRNAs were purchased from Dharmacon Research, Inc (Boulder, Colo.) or produced in-house at ISIS Pharmaceuticals. Sequences of the oligoribonucleotides and their respective modifications are shown in Table 4.

TABLE 4 ASO 5′ C^(E)T^(E)G^(E)C^(E)T^(E)AGCTTCCGGAT^(E)T^(E)T^(E)G^(E)A^(E) 3′ 116847, PS (SEQ ID NO: 11) A 5′ r(CAAAUCCAGAGGCTAGCAG) dTdT sense strand, 271790, PO (SEQ ID NO: 12) dT dT (G U U U A G G U C U C C G A U C G U C)r 5′ antisense Strand, 271766, PO (SEQ ID NO: 13) B 5′ d(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A*G*C′A*G*)2′dT dT sense strand, 335389, PO (SEQ ID NO: 14) dT dT2′(G*T*T*T*A*G*G*T*C*T*CV*G*A*T*C*G*T*C*)d 5′ antisense strand 335390, PO (SEQ ID NO: 15) C 5′ r(C A A A UC C AG A GG C T A G C A G)dTdT sense strand, 271790, PO (SEQ ID NO: 12) dT dT2′(G*T*T*T*A*G*G*T*C*T*C*C*G*A*T*C*G*T*C*)d 5′ antisense strand, 335390, PO (SEQ ID NO: 15) D 5′ d(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A*G*C*A*G*)2′ dTdT sense strand, 335389, PO (SEQ ID NO: 14) dT dT(GU U U AG G U C U C C G A U C G U C)r5′ antisense strand, 271766, PO (SEQ ID NO: 13) E 5′ d(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A*G*C*A*G*)2′ dT dT sense strand, 335389, PO (SEQ ID NO: 14) F 5′d(C*T*G*C*T*A*G*C*C*T*C*T*G*G*A*T*T*T*G*)2′dTdT antisense strand, 335390, PO (SEQ ID NO: 16) C^(E) = 2′-O-methoxyethy1-5-methyl C, T^(E) = 2′-O-methoxyethy1-5-methyl U, G^(E) = 2′-O-methoxyethyl G, A^(E) = 2′-O-methoxyethyl A, PO = phosphodiesters, PS = phosphorothioates, * = 2′,5′-linked-3′-deoxynucleotides,

siRNA duplexes were formed according to the manufacture's instructions; In brief, 1.6 μl of a 250 μM antisense stock solution was combined with 1.6 μl of a 250 μM sense stock solution, 4 μl of 5× universal buffer (500 mM potassium acetate, 150 mM HEPES-KOH, pH 7.4, 10 mM magnesium acetate) and 12.8 μl of ultra-pure water followed by heating at 90° C. for one minute. The reaction was then allowed to cool to ambient temperature for an hour on the bench top. The final concentration of the duplex was 20 μM in 1× universal buffer (100 mM potassium acetate, 30 mM HEPES-KOH, pH 7.4, 2 mM magnesium acetate).

Cell Culture and Transfection. The T-24 cell line utilized in these experiments was obtained from American Type Culture Collection (Manassas, Va.) and was cultured in Dulbecco's modified Eagle's medium (high glucose) (DMEM) supplemented with 10% fetal bovine serum (FBS) (Invitrogen, Carlsbad, Calif.) and Penicillin-Streptomycin (Invitrogen, Carlsbad, Calif.). Twenty-four well dishes were seeded at an initial density of 75,000 cells/well on the day prior to transfection and incubated at 37° C., 5% CO₂. Synthetic siRNA was delivered to cells (typically at 80-95% confluency) by using a Lipofectin reagent (Invitrogen, Carlsbad, Calif.) according to manufacture's instructions. siRNA duplexes, at indicated concentrations, were incubated with 6 μg/ml Lipofectin per 100 nM siRNA in serum free OptiMEM media (Invitrogen, Carlsbad, Calif.) for 10 minutes and then added to each well. After four hours at 37° C., 5% CO₂, the media was aspirated from the cells and replaced with DMEM containing 10% FBS and antibiotics and returned to 37° C., 5% CO₂ until the cells were harvested.

RNA Isolation and RT-PCR. Total cellular RNA was harvested at 18-24 hours post-transfection (unless otherwise noted) on an RNeasy 3000 BioRobot (Qiagen, Valencia, Calif.). In brief, 150 μl RLT Buffer with 1% β-ME was added to each well of a 24-well plate. The samples were then transferred to a 96-well plate for RNA isolation according to the manufacture's protocol (Qiagen, Valencia, Calif.). Reduction of target mRNA expression was determined by real time RT-PCR using an ABI Prism 7700 Sequence Detector (Applied Biosystems, Foster City, Calif.). Reverse-transcription was performed for 30 minutes at 48° C. followed by PCR: 40 cycles of 30 seconds at 94° C. and 1 minute at 68° C. in a total volume of 25 μl. Unless noted, PTEN mRNA expression levels were normalized to c-raf kinase mRNA levels and/or total mRNA levels with Ribogreen (Molecular Probes, Eugene, Oreg.). The gene specific forward (F), reverse (R), and probe sequences (P) are as follows: c-raf kinase (accession number X03484), F: 5′-AGCTTGGAAGACGATCAGCAA (SEQ ID NO:17); R: 5-AAACTGCTGAACTATTGTAGGAGAGATG (SEQ ID NO:18); P: 5′-6-FAM-AGATGCCGTGTTT-GATGGCTCCAGC-TAMRA (SEQ ID NO:19). PTEN (accession number U92436), F: 5′-AATGGCTAAGTGAAGATGACAAT-CAT (SEQ ID NO:20); R: 5′-TGCACATATCATTACACCAG-TTCGT (SEQ ID NO:21); P: 5′-6-FAM-AGATGCCGTGTTTGATGGCTCCAGC-TAMRA (SEQ ID NO:19). Primer/Probe sets were synthesized by Applied Biosystems, (Foster City, Calif.).

FIG. 1 shows the results obtained from the experiments with chimeric siRNA constructs. The activity of chimeric construct C showed comparable activity to that of the control siRNA construct (siPTEN) whereas chimeric constructs A and B were inactive.

EXAMPLE 39 siRNA-Mediated Inhibition of PTEN Message: Effect of 2′,5′-RNA Construct on PTEN mRNA Expression

Inhibition of PTEN expression in a HeLa cell line was evaluated with 2′,5′-siRNA constructs (Tables 5 and 6) and a control sequence using procedures similar to those described in Example 38.

TABLE 5 A 5′ r(C A A A U C C A G A G G C T A G C A G)3′ dTdT sense strand, 271790, PO (SEQ ID NO: 12) dTdT 3′(G U U U A G G U C U C C G A U C G U C)r 5′ antisense Strand, (SEQ ID NO: 13) 271766, PO B 5′ r(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A*G*C*A*G*)2dTdT sense strand, 345899, (SEQ ID NO: 22) PO dTdT2′(G*T*T*T*A*G*G*T*C*T*C*C*G*A*T*C*G*T*C*)r 5′ antisense strand, (SEQ ID NO: 23) 345900, PO C 5′ d(C^(&)A^(&)A^(&)A^(&)U^(&)C^(&)C^(&)A^(&)G^(&)A^(&)G^(&)G^(&)C^(&)T^(&)A^(&)G^(&)C^(&)A^(&)G^(&))2′ dT dT sense strand, 335389, (SEQ ID NO: 24) PO TdTdT2′(G*T*T*T*A*G*G*T*C*T*C*C*G*A*T*C*G*T*C*)r 5′ antisense strand, (SEQ ID NO: 23) 345900, PO D 5′ r(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A*G*C*A*G*)2′ dT dT sense strand, 345899, (SEQ ID NO: 22) PO dTdT2′(G^(&)U^(&)U^(&)U^(&)A^(&)G^(&)G^(&)U^(&)C^(&)U^(&)C^(&)C^(&)G^(&)A^(&)U^(&)C^(&)G^(&)U^(&)C^(&))d antisense strand, 5′ 335390, PO (SEQ ID NO: 25) E 5′ r(C A A A T C C A G A G G C T A G C A G)3′dT dT sense strand, 271790, (SEQ ID NO: 26) PO dT dT 3′(G U U U A G G U C U C C G A U C G U C)r5′ antisense strand, (SEQ ID NO: 13) 344185, PS F 5′ r(C*A*A*A*T*C*C*A*G*A*G*G*C′T*A*G*C′A*G*)2′dTdT) sense strand, 345899, (SEQ ID NO: 22) PO dT dT 3′(G U U U A G G U C U C C G A U C G U C)r 5′ antisense strand, (SEQ ID NO: 13) 344185, PS G 5′ r(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A*G*C*A*G*)2′dTdT sense strand, 345899, (SEQ ID NO: 22) PO dT dT 3′(G U U U A G G U C U C C G A U C G U C)r5′ antisense strand, (SEQ ID NO: 13) 344185, PS * = 2,5′-linked ribonucleotides, PS = phosphorothioates, PO = phosphodiesters, ^(&) = 2′,5′-linked 3′-deoxynucleotides.

TABLE 6 A 5′ r(CAAAUCCAGAGGCTAGCAG) dT dT sense strand, 271790, (SEQ ID NO: 12) PO dT dT (GUUUAGGUCUCCGAUCGUC)r 5′ antisense strand, (SEQ ID NO: 13) 271766, PO B 5′ r(C′A*A*A*T*C*C*A*G*A*G*G*C*T*A*G*C*A*G*)2′dT dT sense strand, 345899, (SEQ ID NO: 22) PO dT dT 3′ (G T T T A G GT C T C C G A T C G T C)r 5′ antisense strand, (SEQ ID NO: 27) 271766, PO C 5′ d(C A A A U C C A G A G G C T A G C A G) 2′ dT sense strand, 271790, dT PO (SEQ ID NO: 12) antisense strand, dTdT2′(G*T*T*T*A*G*G*T*C*T*C*C*G*A*T*C*G*T*C*)r 5′ 345900, PO (SEQ ID NO: 23) D 5′ r(C*U*G*C*T*A*G*C*C*T*C*T*G*G*A*T*T*T*G*)2′ dT dT antisense strand, (SEQ ID NO: 28) 345900, PO E 5′ R(C^(&)A^(&)A^(&)A^(&)T^(&)C^(&)C^(&)A^(&)G^(&)A^(&)G^(&)G^(&)C^(&)T^(&)A^(&)G^(&)C^(&)A^(&)G^(&))3′ddT sense strand, 290244, dTdT PO (SEQ ID NO: 29) antisense strand, dTdT2′(G*U*U*U*A*G*G*U*C*U*C*C*G*A*U*C*G*U*C*)r5′ 345900, PO (SEQ ID NO: 30) F 5′ r(C*A*A*A*T*C*C*A*G*A*G*G*C*T*A*G*C*A*G*)2′ dT dT sense strand, 345899, (SEQ ID NO: 22) PO dT dT 3′(G^(&)U^(&)U^(&)U^(&)A^(&)G^(&)G^(&)U^(&)C^(&)U^(&)C^(&)C^(&)G^(&)A^(&)U^(&)C^(&)G^(&)U^(&)C^(&))r5′ antisense strand, (SEQ ID NO: 31) 290223, PO * = 2,5′-linked ribonucleotides, PS = phosphorothioates, PO = phosphodiesters. A^(&) = 2′-O-methyl A, G^(&) = 2′-O-methyl G, C^(&) = 2′-O-methyl C, U^(&) = 2′-O-methyl U.

Cell Culture and Transfections. The HeLa cell line (CCL-2) utilized in these experiments was obtained from American Type Culture Collection (Manassas, Va.) and was cultured in Dulbecco's modified Eagle's medium (high glucose) (DMEM) supplemented with 10% fetal bovine serum (FBS) (Invitrogen, Carlsbad, Calif.) and Penicillin-Streptomycin (Invitrogen, Carlsbad, Calif.). Twenty-four well dishes were seeded at an initial density of 43,000 cells/well on the day prior to transfection and incubated at 37° C., 5% CO₂. Synthetic siRNA was delivered to cells (typically at 75-85% confluency) by using a Lipofectin reagent (Invitrogen, Carlsbad, Calif.) according to the manufacture's instructions. siRNA duplexes, at indicated concentrations, were incubated with 6 μg/ml Lipofectin per 100 nM siRNA in serum free OptiMEM media (Invitrogen, Carlsbad, Calif.) for 10 minutes and then added to each well. After four hours at 37° C., 5% CO₂, the media was aspirated from the cells and replaced with DMEM containing 10% FBS and antibiotics and returned to 37° C., 5% CO₂ until cells were harvested.

The results of the experiments are summarized in FIGS. 2 and 3. The construct G in Table 5 showed inhibition of PTEN message reduction compared to that of the control A construct (FIG. 2). The ability of 2′,5′-linked antisense RNA: 2′5′-linked DNA duplex to inhibit the PTEN message expression was also examined. The results are summarized in FIG. 2 (Constructs C and D). These constructs were not effective in reducing the message. In another experiment we evaluated 2′,5′-linked RNA constructs with 3,5′-RNA phosphodiesters (FIG. 3, Constructs B and C). The construct B where 2′,5′-RNA was used as the sense strand showed activity at a high dose whereas construct C was inactive. When 2,5′-RNA was used as the antisense strand alone as in D (FIG. 3) it failed to inhibit the target reduction.

EXAMPLE 40 siRNA-Mediated Inhibition of PTEN Message: Effect of Phosphorothioate Linkages

Inhibition of PTEN expression in a HeLa cell line was evaluated with phosphorotioate-linked siRNA constructs (Table 7) and a control sequence (human GADPH) using the procedures outlined below. The “rs” between the linkages designates that the sugar is ribose and the linkage is a phosphorothioate linkage.

HeLa cells were obtained from ATCC, Manassas, Va. and were cultured in DMEM with L-Glutamine medium (Gibco/Invitrogen) supplemented with 10% Fetal Bovine Serum (Hyclone), 0.1 mM Non-Essential Amino Acids, and 1 mM Sodium Pyruvate (Gibco/Invitrogen). For RT-PCR analysis, 96-well plates (Corning Incorporated, #3596) were seeded with 1×10⁴ cells/well. Lipofectin (GIBCO/Invitrogen) transfection reagent was used at a concentration of 3 μl/ml OPTIMEM reduced serum medium (Gibco/Invitrogen)/100 nM siRNA duplex. Lipofectin reagent was incubated with OPTIMEM medium for 30 minutes prior to the addition of siRNA. The desired amount of siRNA was added and mixed. Further 1:1 dilutions were performed in OPTIMEM. Cells were washed twice with 1× phosphate buffered saline and then treated with the siRNA/Lipofectin mixture in OPTIMEM. After a 4 hr incubation period, OPTIMEM medium was replaced with complete growth medium. Cells were harvested after additional 16-20 hrs for RT-PCR analysis.

Total RNA was isolated using RNeasy® 96 kit according to the recommended protocol (Qiagen). Briefly, cells were washed with 200 μl PBS after the removal of growth medium. Following washing, 100 μl buffer RLT was added, and the plate was shaken vigorously for about 20 seconds. To each well 100 μl 70% ethanol were added and mixed by pipetting up and down three times. Samples were then applied into the wells of the RNeasy 96 plate placed in the QIAvac top base of the QIAvac 96 manifold, which was attached to a vacuum source. Vacuum was applied for 30 seconds or until transfer was complete. To each well 80 μl of DNase I incubation mix (20 mM Tris-HCl, pH 8.4, 2 mM MgCl2, 50 mM KCl and 225 Units/ml DNase I from Invitrogen) was added and incubated at room temperature for 30 minutes. Buffer RW1 (1 ml/well) was added and the vacuum was applied for 30 seconds. Buffer RPE (1 ml/well) was added to each well and vacuum was applied for 30 seconds. Washing steps with buffer RW1 and RPE1 wererepeated once more. The plate was then removed from the manifold and blotted dry on paper towels. The plate was placed back in the QIAvac manifold and the vacuum was applied for 10 minutes. To elute RNA 30 μl of RNase-free water was added directly onto the membrane of each well, incubated for 1 minute and vacuum was applied for 30 seconds. In order to maximize the recovery of total RNA the elution step was repeated with additional 30 μl/well RNase-free water.

PTEN and control GAPDH mRNA levels were quantitated by real-time quantitative RT-PCR using the ABI PRISM® 7900 Sequence Detection System (Applied Biosystems). RT-PCR reactions were carried out by adding 15 μl of TaqMan One Step PCR Master Mix (Applied Biosystems, #4309169) reagents (containing 100 nM each of forward primer and reverse primer, and 200 nM probe) to 96-well plates with 10 μl total RNA. The forward PCR primer was: 5′-AATGGCTAAGTGAAGATGACAAT-CAT-3′ (SEQ ID NO:20), and the reverse primer was: 5′-TGCACATATCATTACACCAG-TTCGT-3′ (SEQ ID NO:21). The TaqMan® probe used was 5′-6-FAM-AGATGCCGTGTTTGATGGCTCCAGC-TAMRA-3′ (SEQ ID NO:19) (Biosearch Technologies, Inc.). For human GAPDH, a TaqMan GAPDH Control Reagent Kit was used (Applied Biosystems, #402869). The percentage inhibition for each sample was calculated by comparing the PTEN/GAPDH mRNA ratio for the sample to the PTEN/GAPDH mRNA ratio for the untreated control. The IC₅₀ was derived from the non-linear regression analysis of the percentage inhibition data using GraphPad Prism software (GraphPad Software).

Table 8 summarizes the results of experiments using various dsRNAs which were performed using the methods described herein.

TABLE 7 SEQ ID ISIS NO NO Sequence 48 303912 UrsUrsUrsGrsUrsCrsUrsCrsUrsGrsGrsUrsCrs CrsUrsUrsArsCrsUrsU 32 308746 AAGUAAGGACCAGAGACAAA 49 346280 UrsUrsUrsGrsArsArsArsArsUrsGrsUrsUrsGrs ArsUrsCrsUrsCrsCrsU 50 339078 GGAGAUCAACAUUUUCAAAU 51 346280 UrsUrsUrsGrsArsArsArsArsUrsGrsUrsUrsGrs ArsUrsCrsUrsCrsCrsU 52 343868 GGAGAUCAACAUUUUCAAA 53 346281 UrsUrsUrsGrsArsArsArsArsUrsGrsUrsUrsGrs ArsUrsCrsUrsCrsC 54 343868 GGAGAUCAACAUUUUCAAA 55 339048 AUUUGAAAAUGUUGAUCUCC 56 346286 ArsGrsGrsArsGrsArsUrsCrsArsArsCrsArsUrs UrsUrsUrsCrsArsArsA 57 343867 UUUGAAAAUGUUGAUCUCC 58 346287 GrsGrsArsGrsArsUrsCrsArsArsCrsArsUrsUrs UrsUrsCrsArsArsA r = ribose; s = phosphorothioate

TABLE 8 Antisense:sense SEQ ID NOs IC₅₀ 303912:308746 48:32 1.2185

EXAMPLE 41 siRNA-Mediated Inhibition of PTEN Message: Effect of 2,5′-RNA Gapmer

siRNA constructs with 2′,5′-linked RNA at the 3′ and 5′ends and with 3′,5′-linked ribonucleoside residues in the middle (see below) are synthesized using the procedure described in example 18. Inhibition of PTEN expression in HeLa cell with these constructs is evaluated.

(SEQ ID NO: 32) 5′ PO₃-O-A A G U A A G G A C C A G A G A C A A A 3′ sense strand (SEQ ID NO: 33) 3′ U*U*C*A*U*U C C U G G U C U C U* G* U*U*U*-O- PO₃ 5′ antisense Strand * = 2′,5′-linked 3′-deoxynucleoside residues or 2′,5′-linked ribonucleoside residues phosphorothioate or phosphodiesters, underlined are 3′,5′-linked ribonucleoside residues phosphorothioate or phosphodiesters

EXAMPLE 42 siRNA-Mediated Inhibition of PTEN Message: Effect of 2,5′-RNA Hemimers

siRNA chimeric constructs shown below are synthesized using the procedure described in example 18. Inhibition of PTEN expression in HeLa cell with these constructs is evaluated.

(SEQ ID NO: 32) 5′ PO₃-O-A A G U A A G G A C C A G A G A C A A A 3′ sense strand (SEQ ID NO: 34) 3′ U*U*C*A*U*U C C U G G U C U C U G U U U-O-PO₃ 5′ antisense strand (SEQ ID NO: 32) 5′ PO₃-O-A A G U A A G G A C C A G A G A C A A A 3′ sense strand (SEQ ID NO: 35) 3′ U*U*C*A U U C C U G G U C U C U G U U U-O-PO₃ 5′ antisense strand (SEQ ID NO: 36) 5′ PO₃-O-A A G U A A G G A C C A G A G A * C* A* A* A* 3′ sense strand (SEQ ID NO: 34) 3′ U*U*C*A*U*U C C U G G U C U C U G U U U-O-PO₃ 5′ antisense strand (SEQ ID NO: 37) 5′ PO₃-O-A A G U A A G G A C C A G A G A* C* A* A* A* 3′ sense strand (SEQ ID NO: 38) 3′ U U C A U U C C U G G U C U C U G U U U-O-PO₃ 5′ antisense strand (SEQ ID NO: 39) 5′ PO₃-O-A A G U A A G G A C C A G A G A C A*A*A* 3′ sense strand (SEQ ID NO: 35) 3′ U*U*C*A U U C C U G G U C U C U G U U U-O-PO₃ 5′ antisense strand (SEQ ID NO: 40) 5′ PO₃-O-A A G U A A G G A C C A G A G A CA*A*A* 3′ sense strand (SEQ ID NO: 38) 3′ U U C A U U C C U G G U C U C U G U U U-O-PO₃ 5′ antisense strand * = 2′,5′-linked 3′-deoxynucleoside residues or 2′,5′-linked ribonucleoside residues phospho- rothioate or phosphodiesters, underlined are 3′,5′- linked ribonucleoside residues phosphorothioate or phosphodiesters

EXAMPLE 43 siRNA-Mediated Inhibition of PTEN Message: Effect of 2,5′-RNA Hemimers

siRNA chimeric constructs shown below are synthesized using the procedure described in example 18. Inhibition of PTEN expression in HeLa cells with these constructs is evaluated.

(SEQ ID NO: 41) 5′ PO₃-O-A A G U A A G G A C C A G A G A C A A A 3′ sense strand (SEQ ID NO: 42) 3′ U*U C*A U* U C* C U* G G* U C* U C* U G* U U* U-O-PO₃ 5′ antisense strand * = 2′,5′-linked 3′-deoxynucleoside residues or 2′,5′-linked ribonucleoside residues phospho- rothioate or phosphodiesters, underlined are 3′,5′- linked ribonucleoside residues phosphorothioate or phosphodiesters

EXAMPLE 44 siRNA-Mediated Inhibition of PTEN Message: Effect of 2,5′-Linked RNA Caped 2′-O-Methyl Modified siRNA Constructs

siRNA chimeric constructs shown below are synthesized using the procedure described in example 18. Inhibition of PTEN expression in HeLa cells with these constructs is evaluated.

(SEQ ID NO: 32) 5′ PO₃-O-A A G U A A G G A C C A G A G A C A A A 3′ sense strand (SEQ ID NO: 43) 3′ U*U*C*A^(&) U^(&) U^(&) C C U G G U C U C U G U U U-O- PO₃ 5′ antisense strand (SEQ ID NO: 44) 5′ PO₃-O-A*A*G*U*A* A*G*G*A*C*C*A* G*A*G*A* C* A* A* A* 3′sense strand (SEQ ID NO: 45) 3′ U^(&)U^(&)C^(&) A^(&) U^(&)  U C C U G G U C U C U G U U U-O- PO₃ 5′ antisense strand (SEQ ID NO: 36) 5′ PO₃-O-A A G U A A G G A C C A G A G A * C* A* A* A* 3′ sense strand (SEQ ID NO: 45) 3′ U^(&)U^(&)C^(&)A^(&)U^(&) U C C U G G U C U C U G U U U-O-PO₃ 5′ antisense strand (SEQ ID NO: 37) 5′ PO₃-O-A A G U A A G G A C C A G A G A* C* A* A* A* 3′ sense strand (SEQ ID NO: 47) 3′ U^(&)U ^(&)C ^(&)A^(&) U^(&)  U C C* U* G* G U C U C U G U U U- O-PO₃ 5′ antisense strand (SEQ ID NO: 39) 5′ PO₃-O-A A G U A A G G A C C A G A G A C A*A*A* 3′ sense strand (SEQ ID NO: 46) 3′ U*U*C*A U U C C U G G U C U C U^(&) G^(&) U^(&)  U U-O- PO₃ 5′ antisense strand (SEQ ID NO: 37) 5′ PO₃-O-A A G U A A G G A C C A G A G A* C*A*A*A* 3′ sense strand (SEQ ID NO: 45) 3′ U^(&) U^(&) C^(&) A^(&) U^(&)  U C C U G G U C U C U G U U U-O- PO₃ 5′ antisense Strand * = 2′,5′-linked 3′-deoxynucleoside residues or 2′,5′-linked ribonucleoside residues phospho- rothioate or phosphodiesters, underlined are 3′,5′- linked rib nucleoside residues phosphorothioate or phosphodiesters ^(&) = 2′-O-methyl nucleoside residues

EXAMPLE 45 siRNA-Mediated Inhibition of Survivin Message: Effect of Phosphorothioate Linkages

Inhibition of the expression of Survivin in either HeLa cells or U-87 MG cells was evaluated with siRNA constructs containing alternating phosphodiester and phosphorothioate linkages or containing all phosphorothioate linkages (Tables 9 and 11, respectively) and a control sequence (human GADPH) using the procedures outlined below. The “rs” between the linkages designates that the sugar is ribose and the linkage is a phosphorothioate linkage.

HeLa cells were obtained from ATCC (Manassas, Va.) and were cultured in DMEM with L-Glutamine medium (Gibco/Invitrogen) supplemented with 10% Fetal Bovine Serum (Hyclone), 0.1 mM Non-Essential Amino Acids, and 1 mM Sodium Pyruvate (Gibco/Invitrogen). U-87 human glioblastoma cells were obtained from ATCC (Rockville Md.) and were maintained in Iscove's DMEM medium supplemented with heat-inactivated 10% fetal calf serum.

For RT-PCR analysis, 96-well plates (Corning Incorporated, #3596) were seeded with 1×10⁴ cells/well. Lipofectin (GIBCO/Invitrogen) transfection reagent was used at a concentration of 3 μl/ml OPTIMEM reduced serum medium (Gibco/Invitrogen)/100 nM siRNA duplex. Lipofectin reagent was incubated with OPTIMEM medium for 30 minutes prior to the addition of siRNA. The desired amount of siRNA was added and mixed. Further 1:1 dilutions were performed in OPTIMEM. Cells were washed twice with 1× phosphate buffered saline and then treated with the siRNA/Lipofectin mixture in OPTIMEM. After a 4 hr incubation period, OPTIMEM medium was replaced with complete growth medium. Cells were harvested after additional 16-20 hrs for RT-PCR analysis.

Total RNA was isolated using an RNeasy® 96 kit according to the recommended protocol (Qiagen). Briefly, cells were washed with 200 μl PBS after the removal of growth medium. Following washing, 100 μl buffer RLT was added, and the plate was shaken vigorously for about 20 seconds. To each well 100 μl 70% ethanol were added and mixed by pipetting up and down three times. Samples were then applied into the wells of the RNeasy 96 plate placed in the QIAvac top base of the QIAvac 96 manifold, which was attached to a vacuum source. Vacuum was applied for 30 seconds or until transfer was complete. To each well 80 μl of DNase I incubation mix (20 mM Tris-HCl, pH 8.4, 2 mM MgCl2, 50 mM KCl and 225 Units/ml DNase I from Invitrogen) was added and incubated at room temperature for 30 minutes. Buffer RW1 (1 ml/well) was added and the vacuum was applied for 30 seconds. Buffer RPE (1 ml/well) was added to each well and vacuum was applied for 30 seconds. Washing steps with buffer RW1 and RPE1 were repeated once more. The plate was then removed from the manifold and blotted dry on paper towels. The plate was placed back in the QIAvac manifold and the vacuum was applied for 10 minutes. To elute RNA 30 μl of RNase-free water was added directly onto the membrane of each well, incubated for 1 minute and vacuum was applied for 30 seconds. In order to maximize the recovery of total RNA the elution step was repeated with additional 30 μl/well RNase-free water.

Survivin and control GAPDH mRNA levels were quantitated by real-time quantitative RT-PCR using the ABI PRISM® 7900 Sequence Detection System (Applied Biosystems). RT-PCR reactions were carried out by adding 15 μl of TaqMan One Step PCR Master Mix (Applied Biosystems, #4309169) reagents (containing 100 nM each of forward primer and reverse primer, and 200 nM probe) to 96-well plates with 10 μl total RNA. For human Survivin, the forward PCR primer was: 5′GCACCACTTCCAGGGTTTATTC3′ (SEQ ID NO:76), and the reverse primer was: 5′TCTCCTTTCCTAAGACATTGCTAAGG3′ (SEQ ID NO:77). The Survivin TaqMan® probe used was 5′[FAM]TGGTGCCACCAGCCTTCCTGTG3′ (SEQ ID NO:78) (Biosearch Technologies, Inc.). For human GAPDH, a TaqMan GAPDH Control Reagent Kit was used (Applied Biosystems, #402869). The percentage inhibition for each sample was calculated by comparing the Survivin/GAPDH mRNA ratio for the sample to the Survivin/GAPDH mRNA ratio for the untreated control. The IC₅₀ was derived from the non-linear regression analysis of the percentage inhibition data using GraphPad Prism software (GraphPad Software).

Tables 10 and 12 summarize the results of experiments using various dsRNAs which were performed using the methods described herein.

TABLE 9 Alternating Phosphate/Phosphorothioate Linkages SEQ ID ISIS NO NO SEQUENCE 59 346296 UrsUUrsGArsAArsAUrsGUrsUGrsAUrsCUrsCCrsU 60 346289 AGrsGArsGArsUCrsAArsCArsUUrsUUrsCArsAA 61 339048 AUUUGAAAAUGUUGAUCUCC 60 346289 AGrsGArsGArsUCrsAArsCArsUUrsUUrsCArsAA 61 339048 AUUUGAAAAUGUUGAUCUCC 62 346294 ArsGGrsAGrsAUrsCArsACrsAUrsUUrsUCrsAArsA 63 343867 UUUGAAAAUGUUGAUCUCC 64 346295 GrsGArsGArsUCrsAArsCArsUUrsUUrsCArsAA 65 346283 UUrsUGrsAArsAArsUGrsUUrsGArsUCrsUCrsCU 66 339078 GGAGAUCAACAUUUUCAAAU 67 346284 UUrsUGrsAArsAArsUGrsUUrsGArsUCrsUCrsC 68 343868 GGAGAUCAACAUUUUCAAA 69 346292 UrsUUrsGArsAArsAUrsGUrsUGrsAUrsCUrsCC 68 343868 GGAGAUCAACAUUUUCAAA 59 346296 UrsUUrsGArsAArsAUrsGUrsUGrsAUrsCUrsCCrsU 66 339078 GGAGAUCAACAUUUUCAAAU r = ribose; s = phosphorothioate

TABLE 10 IC₅₀s for Alternating Phosphate/Phosphorothioate Linkages Antisense:Sense SEQ ID NOs CELL LINE IC₅₀ 346296:346289 59:60 U-87 MG 1.76 339048:346289 61:60 HeLa 0.96082 339048:346294 61:62 HeLa 0.24425 343867:346295 63:64 HeLa 0.17701 346283:339078 65:66 HeLa 0.21015 346284:343868 67:68 HeLa 0.97056 346292:343868 69:68 HeLa 0.49071 346296:339078 59:66 HeLa 0.26977

TABLE 11 Phosphorothioate Linkages SEQ ID ISIS NO NO Sequence 70 303912 UrsUrsUrsGrsUrsCrsUrsCrsUrsGrsGrsUrs CrsCrsUrsUrsArsCrsUrsU 32 308746 AAGUAAGGACCAGAGACAAA 71 346280 UrsUrsUrsGrsArsArsArsArsUrsGrsUrsUrs GrsArsUrsCrsUrsCrsCrsU 66 339078 GGAGAUCAACAUUUUCAAAU 71 346280 UrsUrsUrsGrsArsArsArsArsUrsGrsUrsUrs GrsArsUrsCrsUrsCrsCrsU 68 343868 GGAGAUCAACAUUUUCAAA 72 346281 UrsUrsUrsGrsArsArsArsArsUrsGrsUrsUrs GrsArsUrsCrsUrsCrsC 68 343868 GGAGAUCAACAUUUUCAAA 61 339048 AUUUGAAAAUGUUGAUCUCC 73 346286 ArsGrsGrsArsGrsArsUrsCrsArsArsCrsArs UrsUrsUrsUrsCrsArsArsA 63 343867 UUUGAAAAUGUUGAUCUCC 74 346287 GrsGrsArsGrsArsUrsCrsArsArsCrsArsUrs UrsUrsUrsCrsArsArsA r = ribose; s = phosphorothioate

TABLE 12 IC₅₀s for Phosphorothioate Linkages Antisense:Sense SEQ ID NOs Cell Line IC₅₀ 346280:339078 71:66 HeLa 2.2377 346280:343868 71:68 HeLa 1.9085 346281:343868 72:68 HeLa 2.9501 339048:346286 61:73 HeLa 0.40254 343867:346287 63:74 HeLa 0.18763

EXAMPLE 46 Chemically Modified siRNA Targeted to PTEN: In Vivo Study

Six- to seven-week old Balb/c mice (Jackson Laboratory, Bar Harbor, Me.) were injected with compounds targeted to PTEN. Each treatment group was comprised of four animals. Animals were dosed via intraperitoneal injection twice per day for 4.5 days, for a total of 9 doses per animal. Saline-injected animals served as negative controls. Animals were sacrificed 6 hours after the last dose of oligonucleotide was administered, and plasma samples and tissues were harvested. Target reduction in liver was also measured at the conclusion of the study.

Two doses of each treatment were tested. Treatment with ISIS 116847 (5′-CTGCTAGCCTCTGGATTTGA-3′, SEQ ID NO: 75), a 5-10-5 gapmer was administered at doses of 12.5 mg/kg twice daily or at 6.25 mg/kg twice daily. The siRNA compounds described below were administered at doses of 25 mg/kg twice daily or 6.25 mg/kg twice daily. The siRNA is composed of an antisense and complement strand as described in previous examples, with the antisense strand targeted to mouse PTEN. ISIS 116847 (SEQ ID NO:75) and the siRNAs of this experiment also have perfect complementarity with human PTEN.

An siRNA duplex targeted to PTEN is comprised of antisense strand ISIS 341391 (5′-UUGUCUCUGGUCCUUACUU-3′, SEQ ID NO:76) and the sense strand ISIS 341401 (5′-AAGUAAGGACCAGAGACAA-3′, SEQ ID NO:77). Both strands of the ISIS 341391/341401 duplex (SEQ ID NO:76/SEQ ID NO:77) are comprised of ribonucleosides with phosphodiester internucleoside linkages.

A chemically modified siRNA duplex targeted to PTEN is comprised of antisense strand ISIS 359550 (5′-U_(s)UG_(s)UC_(s)TC_(s)UG_(s)GU_(s)CC_(s)UU_(s)AC_(s)UU-3′, SEQ ID NO:78) and the sense strand ISIS 359551 (5′-A_(s)AG_(s)UA_(s)AG_(s)GA_(s)CC_(s)AG_(s)AG_(s)AC_(s)AA-3′, SEQ ID NO:79). Both strands of the ISIS 359550/359551 duplex (SEQ ID NO:78/SEQ ID NO:79) are comprised of ribonucleic acid, with alternating phosphorothioate and phosphodiester internucleoside linkages in the backbone. Positions of the phosphorothioate internucleoside linkages are indicated with a subscripted “s”.

PTEN mRNA levels in liver were measured at the end of the study using real-time PCR and RiboGreen™ RNA quantification reagent (Molecular Probes, Inc. Eugene, Oreg.) as taught in previous examples above. PTEN mRNA levels were determined relative to total RNA (using Ribogreen) or GAPDH expression, prior to normalization to saline-treated control. Results are presented in Table 13 as the average % inhibition of mRNA expression for each treatment group, normalized to saline-injected control.

TABLE 13 Target reduction by chemically modified siRNAs targeted to PTEN in mouse liver Dose (mg/kg, SEQ administered % Inhibition Treatment ID NO 2x/day) Ribogreen GAPDH ISIS 116847 75 12.5 92 95 6.25 92 95 ISIS 341391/341401 76/77 25 12 21 6.25 2 9 ISIS 359550/359551 78/79 25 2 14 6.25 2 26

As shown in Table 13, the ISIS 359550/359551 duplex (SEQ ID NO:78/SEQ ID NO:79), which contains alternating phosphorothioate/phosphodiester internucleoside linkages, caused a decrease in PTEN levels in a dose-dependent manner. The mRNA levels measured for the unmodified ISIS 341391/341401 duplex (SEQ ID NO:76/SEQ ID NO:77) are also suggestive of dose-dependent inhibition.

The effects of treatment with the RNA duplexes on plasma glucose levels were evaluated in the mice treated as described above. Approximate average plasma glucose is presented in Table 14 for each treatment group.

TABLE 14 Effects of chemically modified siRNAs targeted to PTEN on plasma glucose levels in normal mice Dose (mg/kg, administered Plasma glucose Treatment SEQ ID NO 2x/day) (mg/dL) Saline N/A 186 ISIS 116847 75 12.5 169 6.25 166 ISIS 341391/341401 76/77 25 159 6.25 182 ISIS 359550/359551 78/79 25 183 6.25 193

To assess the physiological effects resulting from in vivo siRNA targeted to PTEN mRNA, the mice were evaluated at the end of the treatment period for plasma triglycerides, plasma cholesterol, and plasma transaminase levels. Plasma cholesterol levels from animals treated with either dose of ISIS 116847 (SEQ ID NO:75) were increased about 20% over levels measured for saline-treated animals. Conversely, the cholesterol levels measured for animals treated with either the 25 mg/kg or the 6.25 mg/kg doses of the ISIS 341391/341401 duplex (SEQ ID NO:76/SEQ ID NO:77) were decreased about 12% as compared to saline-treated controls. ISIS 359550/359551 (SEQ ID NO:78/SEQ ID NO:79) did not cause significant alterations in cholesterol levels. All of the treatment groups showed decreased plasma triglycerides as compared to saline-treated control, regardless of treatment dose.

Increases in the transaminases ALT and AST can indicate hepatotoxicity. The transaminase levels measured for mice treated with the siRNA duplexes were not elevated to a level indicative of hepatotoxicity with respect to saline treated control. Treatment with 12.5 mg/kg of ISIS 116847 (SEQ ID NO:75) caused approximately 7-fold and 3-fold increases in ALT and AST levels, respectively. Treatment with the lower dose (6.25 mg/kg) of ISIS 116847 (SEQ ID NO:75) caused approximately 4-fold and 2-fold increases in ALT and AST levels, respectively.

At the end of the study, liver, white adipose tissue (WAT), spleen, and kidney were harvested from animals treated with the oligomeric compounds and were weighed to assess gross organ alterations. Approximate average tissue weights for each treatment group are presented in Table 15.

TABLE 15 Effects of chemically modified siRNAs targeted to PTEN on tissue weight in normal mice Dose (mg/kg, ad- SEQ ID ministered Liver WAT Spleen Kidney Treatment NO 2x/day) Tissue weight (g) Saline N/A 1.0 0.5 0.1 0.3 ISIS 116847 75 12.5 1.1 0.4 0.1 0.3 6.25 1.1 0.4 0.1 0.3 ISIS 76/77 25 1.0 0.3 0.1 0.3 341391/341401 6.25 0.9 0.4 0.1 0.3 ISIS 78/79 25 1.0 0.4 0.1 0.3 359550/359551 6.25 1.0 0.3 0.1 0.3

As shown in Table 15, treatment with antisense oligonucleotides or siRNA duplexes targeted to PTEN did not substantially alter liver, WAT, spleen, or kidney weights in normal mice as compared to the organ weights of mice treated with saline alone. 

What is claimed is:
 1. A composition comprising a first oligomer and a second oligomer, wherein: each of said first and second oligomers, independently, has from 12 to 30 nucleobases; at least a portion of said first oligomer is capable of hybridizing with at least a portion of said second oligomer, at least a portion of said first oligomer is complementary to and capable of hybridizing to a selected target nucleic acid, and at least one of said first or said second oligomers includes at least one 2′-5′ internucleoside linkage, located between the 5′-terminal nucleoside and the adjacent nucleoside of said first or said second oligomers, having the formula:

wherein Y is O or S; and a 5′-modified phosphate group.
 2. The composition of claim 1 wherein said 5′-terminal nucleoside has one of the following formulas:

wherein: Y is O or S; T₃ is said 5′-modified phosphate group; R₁ is H, OH, or OCH₃; R₂ is O—CH₂—CH₂—NH—C(NH)NH₂ or O—CH₂—CH₂—N(CH₃)₂; and B is adenine, guanine, cytosine, uracil, 5-methyl uracil, or 5-methyl cytosine.
 3. The composition of claim 1 wherein said 2′-5′ internucleoside linkage is located on said first oligomer.
 4. The composition of claim 1 wherein said 2′-5′ internucleoside linkage is located on said second oligomer.
 5. The composition of claim 1 wherein said first or second oligomer comprises a 5′-modified phosphate group.
 6. The composition of claim 1 wherein said first and second oligomers are a complementary pair of siRNA oligomers.
 7. The composition of claim 1 wherein said first and second oligomers each comprise at least one 2′-5′ internucleoside linkage.
 8. A composition comprising an oligomer complementary to and capable of hybridizing to a selected target nucleic acid, wherein: said oligomer has from 12 to 30 nucleobases; said oligomer includes at least one 2′-5′ internucleoside linkage, located between the 5′-terminal nucleoside and the adjacent nucleoside, having the formula:

wherein Y is O or S; and wherein said oligomer includes a 5′-modified phosphate group.
 9. The composition of claim 8 wherein said 2′-5′ internucleoside linkage is a 2′-5′ adenosine linkage, 2′-5′ adenosine phosphorothioate linkage, or a 2′-5′ xyloadenosine linkage.
 10. The composition of claim 8 wherein said 5′-terminal nucleoside has of one of the following formulas:

wherein: Y is O or S; R₁ is H, OH, or OCH₃; R₂ is O—CH₂—CH₂—NH—C(NH)NH₂ or O—CH₂—CH₂—N(CH₃)₂; B is adenine, guanine, cytosine, uracil, 5-methyl uracil, or 5-methyl cytosine; and T₃ is said modified phosphate group.
 11. A method of modulating the expression of a target nucleic acid in a cell comprising contacting said cell with a composition of claim
 1. 12. A method of modulating the expression of a target nucleic acid in a cell comprising contacting said cell with a composition of claim
 8. 